Method for producing brushes, in particular interdental brushes, and brush, in particular interdental brush, and product group comprising a plurality of brushes

ABSTRACT

The invention relates to a brush, in particular an interdental brush, which comprises a bristle-carrying stem defining a longitudinal direction and having an elongate support core, a bristle area having bristles projecting from the bristle-carrying stem, and a neck element connecting the support core to a handle, wherein the handle, the support core and the neck element are injection moulded integrally from a first plastics component, and wherein a second plastics component in the form of an integral layer and the bristles projecting therefrom is mounted on the support core. The invention also relates to corresponding product groups and to a corresponding method.

This is a Continuation of application Ser. No. 14/410,536, filed Dec.22, 2014, which in turn is a National Stage of International ApplicationNo. PCT/EP2013/001412, filed on May 14, 2013, which claims priority toEuropean Application No. 12004914.3, filed on Jul. 2, 2012. Thedisclosures of the prior applications are hereby incorporated byreference herein in their entirety.

The present invention relates to a method for producing a brush, inparticular an interdental brush, using the injection molding methodaccording to disclosed embodiments, to a brush, in particular aninterdental brush according to disclosed embodiments and to a productgroup consisting of several brushes according to disclosed embodiments.

Document U.S. Pat. No. 3,698,405 discloses toothpicks having a plasticsmaterial or metal stick, a rubber sponge casing being fastened over theentire length of the stick. Nubs can protrude from the surface of therubber sponge. The rubber sponge is to comprise at least 70% air. In thecase of a further embodiment, the rubber or rubber sponge is fastened tothe stick only over a short distance at the ends thereof.

Document WO 98/16169 discloses an interdental cleaner which consists ofan elongated, stick-shaped carrier produced from a first plasticsmaterial component which is overlapped in part regions of its surface byat least one insert or support produced from a second plastics materialcomponent which is softer than the first plastics material. In thiscase, the insert can be arranged in a recess which is realized in thecarrier and can be held in a positive locking manner with said recess.If the first plastics material component of the carrier and/or thesecond plastics material component of the insert or support includes oneor several additives, the cleaning and care effect can be varied andoptimized. To produce an interdental cleaner of this type, the secondplastics material component of the insert or support is injected ontothe first plastics material component of the carrier, it being possibleto produce the carrier and the insert or support using a two-componentinjection molding method.

In addition, a cleaning instrument for a tooth root canal known fromdocument EP 1 258 227 A includes a head portion and a cleaning portionwhich connects thereto and has a shaft which is provided with bristleson its outer surface. The shaft is realized integrally with the bristlesso that in particular the tooth root canal is able to be cleanedreliably with the cleaning instrument.

In addition, document WO 2008/146968 A discloses a method and a mold toproduce a mascara brush. The mold comprises an upper mold box and alower mold box which together, as a result of molding, in the closedstate form cavities for producing the application heads. A wick producedfrom ceramics or plastics material is inserted into the lower mold boxper mascara brush and once the upper and lower mold boxes have beenmoved together, a soft material is injected into the cavities. To thisend the mold comprises a pressure plate which interacts with the uppermold box, feed passages leading from the space formed by the pressureplate and the upper mold box through the upper mold box into thecavities. Material which is liquefied under pressure, is insertedbetween the pressure plate and the upper mold box. The material isliquefied as a result of moving the pressure plate and the mold boxtoward one another and the liquid material is pressed through theconnecting openings into the cavities.

It is an object of the present invention to propose a particularlysimple injection molding method for producing a brush, in particular aninterdental brush which comprises a bristle-carrying stem, which definesa longitudinal direction and has an elongated support core and a bristlefield with bristles which protrude from the bristle-carrying stem, acorrespondingly produced brush, in particular an interdental brush, aswell as a product group produced from several brushes.

Along with interdental brushes, the brushes can be in particular mascarabrushes, medical brushes, cosmetic brushes, body care brushes, cleaningbrushes, domestic brushes etc.

Said object is achieved with a method according to disclosedembodiments, a brush according to disclosed embodiments and a productgroup according to disclosed embodiments.

Particularly preferred embodiments are provided in the dependent claims.

The solution according to the invention includes a method for producinga brush, in particular an interdental brush which comprises abristle-carrying stem, which defines a longitudinal direction and has anelongated support core, a bristle field with bristles which protrudefrom the bristle-carrying stem and a neck element which connects thesupport core to a handle, having the following steps: inject the handle,the neck element and the support core integrally from a first plasticsmaterial component, introduce the support core in the longitudinaldirection through a bristle field cavity opening of an injection moldinto a bristle field cavity, fix the support core introduced into thebristle field cavity to avoid movement of the support core in thelongitudinal direction and apply a second plastics material componentfrom an injection point of the injection mold onto the support core forrealizing a layer on the support core and the bristles protrudingtherefrom in an integral manner; as well as a brush, in particular aninterdental brush, comprising a bristle-carrying stem, which defines alongitudinal direction and has an elongated support core, a bristlefield with bristles which protrude from the bristle-carrying stem and aneck element which connects the support core to a handle, wherein thehandle, the support core and the neck element are injected integrallyfrom a first plastics material component, and wherein a second plasticsmaterial component in the form of an integral layer and the bristlesprotruding from said layer is applied onto the support core. Thesolution according to the invention also includes a product groupcomprising several brushes, in particular interdental brushes, whereinthe handles of the adjacent brushes are connected in each case by meansof one, preferably by means of two, material bridges produced from thefirst plastics material component as well as a product group comprisingseveral brushes, in particular interdental brushes, wherein the handlesof the adjacent brushes are connected in each case by means of amaterial bridge produced from the first plastics material component anda material bridge produced from the second plastics material component.

A product group consists of three to eight products which are arrangedtogether and preferably of five to six products. For reasons ofsimplicity, the figures are shown in each case with only five products.

In addition, the solution according to the invention includes a methodfor producing a brush, in particular an interdental brush whichcomprises a bristle-carrying stem, which defines a longitudinaldirection and has an elongated support core, a bristle field withbristles which protrude from the bristle-carrying stem and a neckelement which connects the support core to a handle, having thefollowing steps: inject the handle, the neck element and the supportcore integrally from a first plastics material component, move theinjected part into a further cavity of an injection mold with bristlecavities, fix the part introduced into the bristle field cavity to avoidmovement of the support core in the longitudinal direction, and apply asecond plastics material component from an injection point of theinjection mold onto the support core for realizing a layer on thesupport core and the bristles protruding therefrom in an integralmanner.

The moving in the injection mold preferably occurs using a transport barwhich, after a lifting movement, moves the at least partially finishedproducts out of the cavity, as a result of a translatory displacement ora rotation, to a further cavity where they are placed in the cavity bymeans a stroke.

The transport bar is preferably part of the cavity, this means that thetransport bar forms part of the forming geometry at least in the firstinjection molding operation. The interface between the product and thetransport system can be arranged, for example, in the handle or in theneck or as a combination therefrom.

The often desired individualization of the product can be achieved inthe handle and in the neck, for example, by exchangeable shaping parts.For example, lettering or other surface geometries can be formed in thisway. Said elements can be arranged both in the transport bar and in theactual cavity.

The production process of the named products is ended after theinjection molding insofar as usable products are present. The productcan be packaged correspondingly after the injection molding.

The products are preferably packaged in a packaging which is availableto the consumer as a box. The products are arranged therein in ahorizontal manner or abutting against one another vertically.

The connecting of the packaging process can be effected inline, i.e.interlinked or offline in a separate step. In the case of the inlineprocess, the injection molding and the packaging are coupled. Theproducts are not removed out of the machine until they are completelypackaged. In the case of the offline process, the products are stored,transported, etc. after the injection molding process, rather than beingpackaged beforehand.

In addition, it is possible to carry out intermediate steps after theinjection molding and prior to the packaging. For example, buffering ortreating the product, for example as a result of coating (spraying,dipping, etc.).

A hard plastics material is preferably used as the first plasticsmaterial component from which the handle, the support core and the hardelement are integrally formed and a soft component is preferably usedfor the second plastics material component from which the layer or thebristles protruding from the same are formed. It is naturally alsopossible for a further third component to be used, for example in theregion of the handle, to increase the grip and to improve theergonomics, or else also in the region of the bristle field in the formof further cleaning elements or other functional elements. Examples ofthe materials that are possible in this context are provided furtherbelow in the general description part.

With regard to the product groups according to the invention, it isnoted that in principle each product can be produced in an individualcavity and each product can be accommodated individually in the salesunit. In general, several products are preferably arranged side by sideand the connection between the products is effected by means of materialbridges in the handle region. The longitudinal axes of the brushes arepreferably arranged in parallel. As a rule, one, two or three materialbridges are provided (however more are conceivable). Said materialbridges impart stability above all to the product groups. The productsare separated additionally at the material bridges for use. Since, whenthe individual brushes are separated off, edges which could injure finetissue, such as the oral mucosa, can be created, the material bridgesare regularly arranged in the handle. The material bridges arepreferably produced in each case from the same component. It is alsopossible for two different or several different components to be used,one each being used per material bridge. This depends, however, on thechosen injection point, only one injection point being used for eachcomponent preferably per product group. In a further preferred manner,one material bridge is arranged rather in the front part and the otherrather in the rear part of the handle so that a sufficient distance isensured between the material bridges. The material bridges can be formedin a rectangular or oval manner in cross section and the cross sectionpreferably has a longer and a shorter length and the longer length ofthe cross section preferably lies in the direction of the longitudinalaxis of the product. The material bridges can additionally includeelements for support during the separating operation such as, forexample, notches or perforations as predetermined breaking points. Withregard to the product development, it has proved expedient to providethe identical materials and identical geometries for all the products ofa product group. However, it is also possible to develop the products ina different manner, in this case the forms of the cleaning tips can varysomewhat. Different diameters, different length of the cleaning tips anddifferent overall lengths of the brushes can be provided. With regard tothe material, variation can be undertaken in the case of the secondcomponent (i.e. the soft component).

In a preferred embodiment of the present invention, the second plasticsmaterial component surrounds the preferably bristle-free neck element atmost in part.

This depends in each case on the choice of injection points, howeverembodiments are also possible where the neck element is completelyencased by the second component.

In a further preferred embodiment of the present invention, the supportcore, the neck element and the handle are injected in a cavity of theinjection mold that is separate from the bristle field cavity.

In this way the production process can be developed more efficientlythan if a completely different injection mold has to be used for thispurpose.

In yet another preferred embodiment of the present invention, the layeris realized in such a manner that it forms a casing of the support corein the region of the bristle stem.

A particularly good and secure seat can be achieved on the support coreby means of such a casing. In particular, with regard to its shrinkage,the second component can also be chosen such that it shrinks onto thesupport core.

In another preferred embodiment of the present invention, the supportcore is centered in the bristle field cavity by means of bristle fieldmold parts, preferably by means of support elements which protrude inthe direction toward the interior of the bristle field cavity, atseveral support points which are spaced apart from one another in thelongitudinal direction.

The support points are preferably arranged between the bristles.

In this way, the support core can be effectively prevented from movingin the radial direction (i.e. away from the longitudinal axis) and whereapplicable from closing the openings for the bristles to be formed.

In yet another preferred embodiment of the present invention, the fixingof the support core is effected in the region of the handle preferablyat points at which only one plastics material component is present.

In this way, a second, possibly softer plastics material componentshould be prevented from being damaged by the fixing agent.

In a further preferred embodiment of the present invention, the firstand second plastics material components consist of a hard material, ahard material and a semi-hard material or else a hard material and asoft material.

The material combinations chosen in each case depend on the specificapplication and the materials used are given specifically further belowin the general description part. For example, a PE/PE material pairingis possible for the hard/semi-hard combination, an HDPE being used forthe first material component and an LLDPE being used for the secondmaterial component. A PP/TPE material pairing is possible for thehard/soft combination.

The materials used can be water-soluble and edible and thus, forexample, be formed completely or in part from hydrocolloids, starches,gum arabic, polyvinyl alcohol or Polyox.

In addition, it is possible as a further component, to spray on amaterial or to dip the existing product in a bath and thus apply afurther component, for example as a coating.

Means which can be used as a coating or as constituents for theabovementioned materials are, for example, color, flavor, tooth-cleaningfluid, toothpaste and active substances.

In addition, the support core preferably comprises a smaller diameterthan the neck element.

This ensures that the support core is not too thick at its front end foruse in the interdental area.

In a preferred manner, in addition, the layer is injected or appliedonto the support core so as to be flush with the neck element.

The flush closure of the layer with the neck element is more pleasing tohandle and offers a more advantageous development visually.

In another preferred embodiment of the present invention, the injectionpoint of the second plastics material component is situated on the frontend of the handle, the end facing the neck element.

In principle, the choice of the injection point is determined by thedevelopment of the product, the shot weight and the possibilities of theprocessing machine. Both hot runner and cold runner systems can be used.In the case of classic injection molds with a cold runner system, thegating system is not insulated thermally from the rest of the mold.Consequently, both the mold and the gating system located therein aretempered at temperatures clearly below the processing temperatures ofthe plastics. As a result, the thermoplastic material also solidifies inthe gating system during the production of a component.

In the case of a hot runner system the gating system is separatedthermally from the rest of the mold and is separately heated such thatthe plastic melt in the gating system remains flowable. As a result, theplastics material does not solidify in the gating system and no sprueremains on the component. In addition, longer flow paths can also berealized as a result of the hot runner systems because the pressure lossin the gating system is not increased by cooling of the melt or the risein viscosity connected thereto.

On account of the above-mentioned choice of the injection point, theplastics material component of the casing on the handle overlaps a smallpart of the surface, whilst, on the rear side of the interdental brush,on the neck element, it covers a considerable part of the surface of oneside before it finally covers the surface in the bristle field portioncompletely. The parts injected from the first plastics materialcomponent (handle, neck element and support core) comprise, whereapplicable, corresponding troughs or channels which enable or supportthe flowing of the second plastics material component. Reverse injectionmolds are used in each case in a corresponding manner. The injectionnozzle, in the case of said embodiment, is arranged in the handle cavityand a hot runner system is preferably used on account of the flow path.

In yet another preferred embodiment of the present invention, theinjection point of the second plastics material component is situated atthe exposed end of the support core or at the end of the support corefacing the neck element.

If the injection point is arranged at the exposed end of the supportcore, a separate injection point is provided for each brush. A coldrunner system is used as a rule in this connection, additional meansbeing provided in the mold or during post-processing for separating theproduct from the sprue. In general, punches or cutters are possible asseparating means. The injection nozzles are consequently arranged ineach case in the bristle field cavity and both tunnel-gating andfilm-gating or other known gating types can be used.

In yet another preferred embodiment of the present invention, theinjection point of the second plastics material component is situated onthe rear end of the handle, the end remote from the neck element.

In this case, the injection nozzle is once again arranged in the handlecavity. As a rule, a hot runner system is used on account of therelatively long flow path. In this case, the second plastics materialcomponent overlaps a large part of the surface of the handle as well as,on the rear side of the interdental brush, on the neck element, aconsiderable part of the surface of one side before it once againcompletely covers the surface in the bristle field portion.

The second plastics material component, in this case, is received incorresponding troughs or in a hole in the handle where it forms aportion with increased grip.

A corresponding trough in the handle can be provided with a structuresuch as, for instance, a structure on the edge or on the bottom of thetrough. The form of the structure can comprise nubs, grooves, lamellaeor similar as well as combinations thereof. One or several componentscan project through one another, for example hard components can projectthrough soft components.

The trough can be developed with a two-component or three-componentlining for further improving the grip and ergonomics.

In addition, it is possible to provide transitions in the form of softtransitions from the handle, or else hard offset transitions from thehandle, such as, for instance, with an offset indentation.

In principle, closed or open troughs can be provided, wherein in theclosed version of the edge the trough is continuous and wherein in theopen version the trough is open at least at one end (for example guideson the left and right in the direction of the longitudinal axis). It isalso conceivable for the trough to be open at the front and rear.

Different developments are also conceivable with regard to embodimentswith a hole in the handle. There can be one or several holes present,for example there can be one large hole and several small holes. Theholes are preferably developed in a circular or oval manner, however,n-angle or polygonal holes (with rounded corners for example) areconceivable.

In addition, combinations of troughs and holes are also possible, as arealso, for instance, holes inside a trough.

In addition, the support core preferably comprises a round, triangularor trapezoidal cross section.

As a rule, the cross sectional form of the support core depends on thespecially chosen geometry of the bristle field. In addition, it ispossible for the support core not to be surrounded at all or onlysurrounded in part by the casing or layer on one side (as a rule thebottom surface). The support core does not then comprise any bristleseither on said side.

In another preferred embodiment of the present invention, the supportcore, and preferably also the bristle stem, tapers in the direction ofits end remote from the neck element.

The tapering development of the support core as well as preferably alsoof the bristle stem ensure greater variability of the brush andcontribute, where applicable, to the ease in which the brush is able tobe moved into the interdental area.

In a preferred embodiment of the present invention, the handle compriseson its end remote from the neck element a notch which is preferablyprovided with a border from a soft component.

Using the notch, the brush is able to be mounted on a retaining deviceor else a glass or a beaker. The border with the soft component canincrease the grip when putting it on as well as provide protectionagainst scratching or damage.

The bristles preferably protrude in a non-radial manner from thelongitudinal axis of the support core.

The individual bristles or rows of bristles protrude in factsubstantially vertically from the longitudinal axis of the support coreor else they lie horizontally within a plane which runs through thelongitudinal axis or else runs below the longitudinal axis. The cleaningeffect of the brush can be improved in the critical areas in theinterdental spaces in this manner.

In a preferred manner, in addition, the bristles reduce in length in thedirection of the end of the bristle stem remote from the neck element.

Said measure also serves for improving the cleaning effect in theinterdental spaces as the form of the brush can be better adapted.

In another preferred embodiment of the present invention, two rows ofbristles protrude substantially horizontally from the support core in aplane below the longitudinal axis of the support core.

In another preferred embodiment of the present invention, three rows ofbristles, which converge in the direction of the end of the bristle stemremote from the neck element and which preferably protrude substantiallyvertically from the top surface, are arranged on the top surface of thesupport core.

As a result of said two measures, a perfectly complementing bristlefield geometry can be created with which the interdental areas are ableto be treated completely and uniformly. The non-radial arrangement ofthe rows of bristles in each case strengthens the cleaning effectcompared to a radial arrangement of the same.

In a further preferred embodiment of the present invention, the secondplastics material component is injected onto the front end of thehandle, facing the neck element, wherein the second plastics materialcomponent overlaps a small part of the surface on the handle whilst itcovers a substantial part of the surface on the rear side of the neckelement and covers the surface of the support core completely, or elsewith the exception of a bottom side.

In a further preferred embodiment of the present invention, the secondplastics material component is injected onto the front end of thesupport core, remote from the neck element, wherein the second plasticsmaterial component covers the surface of the support core completely, orelse with the exception of a bottom side.

In a preferred embodiment of the present invention, two rows ofbristles, which converge in the direction of the end of the bristle stemremote from the neck element and which protrude from the top surfacepreferably inclined outward, are arranged on the top side of the supportcore.

Here too, the two rows of bristles converge in the direction of theexposed end of the support core and the length of the individualbristles reduces in the direction of the exposed end of the supportcore. Said variant is somewhat simpler to produce than the variant withthe three rows of bristles on the top surface of the support core. Onceagain, a somewhat modified cleaning effect is also produced. Inprinciple, however, the number of rows of bristles can be chosenarbitrarily, a number between two and nine being preferred and a numberbetween three and five being preferred even more.

The angle between the individual rows of bristles is a maximum of 180°,i.e. in each case the angle between the two rows of bristles which arethe furthest apart. In another preferred embodiment, the angle isbetween 0° and 90°. In the case of the rows arranged in the center (onthe top surface), the angle is, where applicable, between 0° and 20°; inthe case of the rows arranged on the edge, the angle, in a preferredmanner, is between 60° and 85°.

Further cleaning or polishing elements as well as further functionalelements such as, for example, flossers (also known as dental floss tapeor dental violins), toothpicks and tongue cleaners are suitable aspossibilities for combination with the present product. Lamellae fromthe second material component can also be arranged on the support core.

The lamellae can be incorporated in the bristle field in differentforms. For example, the lamellae can run around the support core in ahelical manner, they can be arranged in disk-shaped manner around thesupport core and in this way several lamellae can also be arranged onebehind another. In addition, it is possible to arrange longitudinallamellae which extend along the longitudinal axis. Lamellae can bedeveloped generally in a linear or also wave-shaped manner and thecontour can be closed or open. In addition, the lamellae can realize anelevation profile.

The lamellae can be arranged in combination with the other namedcleaning elements and, in particular, the lamellae can be arrangedbetween the bristles.

With regard to the dimension of the brush according to the invention, alength of between 35 and 70 mm is preferred and a length of between 40and 55 mm is preferred the most. In a preferred manner the height(including the bristle field) is between 0.8 and 2.8 mm and in the mostpreferred manner is between 1 and 2 mm. The width of the brush accordingto the invention is between 3 and 12 mm and in the most preferred mannerbetween 5 and 8 mm.

In yet another further preferred embodiment of the present invention,the second plastics material component is injected onto the rear end ofthe handle, remote from the neck element, wherein the second plasticsmaterial component overlaps a large part of the surface on the handle,whilst it covers a substantial part of the surface on the rear side ofthe neck element and covers the surface of the support core completely,or else with the exception of a bottom side.

In addition, a brush is provided, in particular an interdental brush,comprising a handle, a neck element and a support core, wherein the neckelement connects the handle and the support core and wherein a bristlefield is applied onto the support core, and wherein the handle comprisesa notch on its end remote from the neck part.

In a preferred manner, the notch is surrounded by two lateral flanks ofthe handle which are additionally developed in a flexible or resilientmanner in the form of clamping arms. The flexibility of the two clampingarms can be formed as a result of the geometry of the same and/or as aresult of the plastics materials or material combinations chosen.

The basic body, which at all events includes the handle and the neckelement (these can however also be injected integrally with the supportcore), is regularly formed from a plastics material component,preferably a hard material.

The notch is preferably surrounded by a border produced from a softcomponent in order to ensure a better hold. The notch, however, can alsobe developed in a membrane-like manner with a soft component layer whichis formed in a lip-like manner around the object inserted in each case.

Over and above this, the surface in the region of the notch can beprovided such that said region includes a trough for holding the brush.In addition, surface elements, such as, for instance, lamellae and nubsamong others, can be arranged in the region of the notch in order toimprove the grip further.

Along with the named and described application on interdental brushes,the functional element of the notch can be used in general in manualoral hygiene appliances. For example, also on other interdental cleaningdevices, toothbrushes, flossers, etc.

In a further development, a brush, in particular an interdental brush,which comprises a bristle-carrying stem, which defines a longitudinaldirection and has an support core which extends in the longitudinaldirection, and a bristle field with bristles which protrude from thebristle-carrying stem, is produced using the injection molding method.

A bristle field cavity, which serves for producing the bristle-carryingstem and the bristles, is closed for this purpose. This occurs as aresult of moving the mold parts of the injection mold, which define thebristle field cavity, into the closed state. The bristle field cavity,thus closed, comprises a bristle field cavity opening.

A support core arranged with its longitudinal extension in thelongitudinal direction is inserted into the closed bristle cavity in thelongitudinal direction through the bristle field cavity opening. Theinserted support core preferably projects out of the bristle fieldcavity beyond the bristle field cavity opening by way of a portion.

The support core inserted into the closed bristle field cavity is fixedin such a manner that it cannot be moved, i.e. displaced, in thelongitudinal direction.

As a result of subsequently introducing plastics material into thebristle field cavity, a layer of plastics material is injected onto thesupport core and the bristles are simultaneously produced integrallywith the layer.

The fixing of the support core prevents it from being able to bedisplaced in the longitudinal direction as a result of the force exertedon it by the liquid plastics material.

The advantage of inserting the support core into the already closedbristle field cavity is that damage to both the injection mold and thesupport core when closing the bristle field cavity is avoided. Theinserting of the support core into the opened bristle field cavity, inthe case of even small distortions of the support core, could result,when the bristle field cavity was closed, in its becoming jammed in theinjection mold and said mold being damaged as a result.

In a preferred manner, an injection mold is provided with at least twobristle field mold parts which in the closed state definethe—closed—bristle field cavity. The bristle field cavity comprises abristle field cavity opening on an end face. Said opening is situated atan end of the bristle field cavity in the longitudinal direction.

Once the bristle field mold parts have been moved into the closed state,the support core is inserted in the longitudinal direction through thebristle field cavity opening into the bristle field cavity and is fixedby means of a fixing element. As a result of injecting plastics materialinto the bristle field cavity, the layer and at the same time thebristles are realized on the support core.

In a preferred manner, the layer is realized as a casing of the supportcore in such a manner that the support core cannot come into contactwith the teeth when the interdental brush is applied. This offers thepossibility of a metal wire, for example of spring steel, being able tobe used as support core, the risk of a galvanic shock being prevented.

In a preferred manner, the plastics material is injected such that itflows into the bristle field cavity through the bristle field cavityopening.

The end of the support core, which is located in the bristle fieldcavity, is completely injected around by plastics material in aparticularly preferred manner such that the casing forms a type of caparound the support core at the exposed end of the bristle stem.

In a preferred embodiment the support core is retained by means of thefixing element outside the bristle field to be formed—in thelongitudinal direction—and the plastics material is injected in such amanner that it flows through the bristle field cavity opening into thebristle field cavity. The support core is consequently retained upstreamin front of the bristles to be formed, which makes it possible for thesupport core to be able to extend over at least approximately the entirelength of the bristle field cavity without there being any risk of itbeing bent by the plastics material flowing into the bristle fieldcavity.

The bristle field cavity can comprise a bristle field portion and, inthe direction toward the bristle field cavity opening, connectingdirectly thereto, a neck portion for this purpose.

In a preferred manner, the support core is not fixed in a completelyrigid manner, but the fixing is effected on a portion, in particular endportion of the support core, whilst the non-fixed part is able to bemoved radially in the bristle field cavity. As a result, the fixing issecured purely in an axial manner.

That part of the interdental brush which comprises the injected bristlesand which is intended for the purpose of being inserted into theinterdental spaces when the interdental brush is applied, is produced inthe bristle field portion.

The neck portion can consequently be realized greater than the diameterfor the bristle-carrying stem in the bristle field portion.

In a preferred manner, the injection mold however comprises at least oneneck mold part and the support core is retained during the injecting ofthe plastic material by means of the fixing element in the region of theneck mold part. The neck mold part is situated in this case on the sideof the bristle field mold part on which the bristle field cavity openingis located.

In a further preferred embodiment, the injection mold comprises a capmold part with a cap cavity which serves for realizing the layer, forexample the casing at the exposed end of the bristle stem.

In a preferred manner the cap mold part abuts directly against thebristle field mold part.

In this case, the cap mold parts together with the bristle field moldparts and, where applicable, the neck mold parts and the fixing elementare designated as the first mold part.

In a preferred manner, in the closed state two neck mold parts form aneck cavity, the neck cavity opening of which, when the plasticsmaterial is injected, is arranged abutting against the bristle fieldcavity opening. This enables the simultaneous and integral production ofthe layer or the casing and the bristles together with a neck cover orneck layer about the support core.

In a preferred manner, the fixing element is formed by two clampingpunches which are located diametrically opposite one another withreference to the longitudinal direction and are movable toward oneanother from a rest position into a clamping position in order to holdthe support core clampingly in the clamping position. In a preferredmanner, the direction of movement of the clamping punches runs along acommon straight line which extends at right angles to the longitudinaldirection. The direction of movement, in this connection, is preferablyparallel to the opening direction of the handle cavity and of the neckcavity.

In a preferred manner, the clamping punches engage into the interior ofthe neck cavity in their clamping position and are flowed around byplastics material during the injection molding. In a preferred manner,in this case, the clamping punches seal in relation to the support coresuch that the plastics material is not able to flow into the clampingregion when said plastics material flows around the punch pairing.

This leads to the plastics material component of the interdental brushcomprising recesses which are created by the clamping punches, or apassage created thereby through which the support core extends.

In a preferred manner, the support core is completely enclosed in thecircumferential direction by the clamping punches which are moved intothe clamping position such that a relevant fixing portion of the supportcore remains free of plastics material. In the passage of the plasticsmaterial formed as a result, the support core is free—without beingencased by the plastics material. The support core preferably lies sodeeply in the passage or recess that the risk of a galvanic shock whenteeth are contacted is averted as the teeth are not able to contact it.

In order to achieve a particularly secure fixing of the support core, ina preferred manner the clamping punches comprise, in the end regionswhich face one another, teeth or tooth spaces which mesh with oneanother in the clamping position.

In a preferred manner, the support core is centered in the bristle fieldcavity—in the bristle field portion—at several support points which arespaced apart from one another in the longitudinal direction by means ofbristle field mold parts. The bristle field mold parts comprise supportelements which preferably protrude in the direction toward the interiorof the bristle field cavity for this purpose.

In a preferred manner, the support elements protrude by between 0.08 mmand 0.16 mm, in a particularly preferred manner between 0.1 mm and 0.14mm, in relation to the outside surface of the part of the bristle fieldcavity defining the bristle-carrying stem.

In addition, in a preferred manner the support elements are realizedwith reference to the support core in such a manner that, when measuredin the radial direction, a gap of between 0.01 mm and 0.03 mm, in aparticularly preferred manner of between 0.015 mm and 0.025 mm, remainsbetween the support elements and the central or centrally imaginedbristle-carrying stem. As a result, the support core can be inserted inthe longitudinal direction into the bristle field cavity and between thesupport elements without any obstacle or deflection occurring. Inaddition, this makes it possible, during injection of the plasticsmaterial, to form a thin skin of plastics material on the support coreat the support elements.

When viewed in the longitudinal direction, the support core is supportedin an angularly offset manner by means of the support elements, in apreferred manner one following after another. The offset is preferably90°. As a result, the support elements are spaced apart from one anotherin the longitudinal direction and no support elements are opposite oneanother in the radial direction. The plastics material can consequentlyflow practically unobstructedly from the bristle field cavity openingthrough the bristle field cavity as it is restricted in cross section ata maximum of one point. In this way, the support elements realizesupport points which are realized in a helical manner around thebristle-carrying stem.

In a preferred manner, the support points are arranged in such a mannerthat the distance between two support points on the same side is between4 and 16 times and preferably 4 times a distance between bristles.

The last support point toward the exposed end of the support core ispreferably situated directly after the last bristle plane or directly infront of the last bristle plane.

The support points are preferably arranged in a uniform manner. However,it is also possible for the distance between support points in thelongitudinal direction not to be always the same.

The support points are preferably developed identically over the entirebristle field. Their number is defined by the length of thebristle-carrying stem and the distance between the support points.

The support points or support elements are arranged in such a mannerthat the bristle holes in the bristle field cavity are not able to beclosed by the support core and the realizing of all the bristles isconsequently ensured.

Bristle holes are to be understood as those parts of the bristle fieldcavity which proceed from the outside surface which determines thebristle-carrying stem and serve for forming the bristles.

In a preferred manner, the support core is formed by a metal wire,preferably from a stainless or rust-resistant spring steel. A 1.4310steel is the most preferred. The yield strength of the metal wire shouldbe greater than 2000 N/mm². This ensures good restoring torque whenbending the bristle-carrying stem in the application and prevents thesupport core breaking when bent multiple times.

As an alternative to this, the support core can also consist of plasticsmaterial, ceramic or carbon-composite fibers.

Plastics material support cores can be produced by means of injectionmolding or extrusion. A reinforced plastics material is preferably usedin order to obtain the necessary rigidity and hardness. Glass fibers orglass balls can preferably be used to reinforce the plastics material.

The injection molding or extrusion process for a plastics materialsupport core is connected upstream of the injection molding process forthe bristle field and can be separate or incorporated in the sameinjection mold (two or multiple component mold). The plastics materialsupport core can be in a form that deviates from a wire and can define asubstantial proportion of the handle part and at best the surfacethereof.

In a preferred manner, a handle part of the interdental brush is alsoproduced by means of the plastics material during the injection moldingof the bristle field.

In this case, the handle part is injected in a handle mold part and thisis also designated here as a second mold part.

For the abovementioned purpose, the injection mold preferably comprisestwo handle mold parts which, in the closed position, form a handlecavity with a handle cavity opening at an end face (second mold part).The bristle field mold parts, which are moved into the closed state,together with the support core, which is inserted into the first fieldcavity and is held by means of the fixing element, are moved to thehandle-mold parts in such a manner that the end faces of the bristlefield mold parts (or neck mold parts) and handle mold parts abut againstone another and the bristle field cavity opening or further neck cavityopening is located at the handle cavity opening.

The bristle field cavity, where applicable with the cap cavity and thehandle cavity, where applicable together with the neck cavity,consequently together form an injection cavity for the entire plasticsmaterial component of the interdental brush.

Said embodiment enables the plastics material to be injected into thehandle cavity. It then flows through the handle cavity opening andbristle field cavity opening which are located close together with theneck cavity, or the neck cavity openings, interposed, into the bristlefield cavity. An injection point in the region of the bristle fieldcavity can be avoided as a result.

It is also possible to inject the plastics material directly into thebristle field cavity by means of a corresponding injection point toproduce the layer or casing and the bristles.

In this case, the bristle field cavity opening can serve as closure ofthe bristle field cavity such that a portion of the support core whichprotrudes beyond the bristle material is not injected around by theplastics material. This enables the production of interdental brusheswhich can be fastened on a separate handle in a known manner.

It is also possible in a corresponding manner for the further neckcavity opening to form the closure of the injection cavity and thesupport core to protrude through said opening such that the protrudingportion is not injected around with plastics material.

The brush, in particular the interdental brush which is produced incompliance with the method according to the further development, whetherit comprises a handle part or does not comprise a handle part, has abristle-carrying stem, which defines the longitudinal direction and hasan elongated support core which extends in the longitudinal direction,and bristles which protrude from the bristle stem. A layer is injectedon the support core by means of plastics material or it is injectedaround by means of the plastics material, the plastics materialrealizing the layer or a casing of the support core and the bristles inan integral manner.

In a preferred manner, a fixing portion of the support core is at leastpartially exposed; the support core is not overlapped by the plasticsmaterial at the point that is exposed. In a preferred manner, saidfixing portion is situated outside the region in which the bristles aresituated.

In a preferred manner, the support core is partially exposed at thesupport points or at the support points is only coated by a plasticsmaterial film which is thin when compared to the remaining region of theplastics material of the casing. It must be mentioned that said supportpoints are defined by the support elements which are explained furtherabove.

If, in the case of an interdental brush, a support core produced fromelectrically conducting material, or a metal wire, is used, the exposedpoints are arranged in such a manner that the support core is not ableto come into contact with the teeth.

In a preferred manner, the bristles protrude from the bristle-carryingstem in the radial direction.

In a further preferred manner, the bristles are arranged in bristle rowswhich extend in the longitudinal direction and are uniformly distributedin the circumferential direction. In addition, the bristles arepreferably and additionally arranged in bristle planes which extend atright angles to the longitudinal direction and are spaced apart from oneanother in the longitudinal direction. Each bristle of a row of bristlesis then also situated in a bristle plane.

In a preferred manner, the support points are situated in each casebetween successive bristle planes.

It must be mentioned at this point that the corresponding embodiment ofthe bristle field cavity is obviously also defined by means of theabovementioned arrangement of the bristles.

The injection mold comprises at least two bristle field mold parts whichcan be moved from an open state into a closed state. In the closedstate, the bristle field mold parts define a bristle field cavity forproducing the bristle-carrying stem and the bristles of the brush, inparticular the interdental brush, as a result of injection molding theplastics material. In the closed state of the bristle field mold parts,the bristle field cavity, on an end face—and consequently on an end faceof the bristle field mold parts, comprises a bristle field cavityopening. A support core can be inserted through said opening in eachcase in the longitudinal direction into the bristle field cavity. Inaddition, there is a fixing element which serves for fixing the supportcore inserted into the bristle field cavity.

Depending on the arrangement of the bristles, it can be necessary toprovide more than two bristle field mold parts which form the bristlefield cavity in the closed state. Forced removal from the mold can beavoided as a result.

In a preferred manner, the injection mold comprises two handle moldparts which can be moved from an open position into a closed position.In the closed position, the handle mold parts define a handle cavitywith a handle cavity opening, said handle cavity serving for injectionmolding a handle part of the brush, in particular of the interdentalbrush. The bristle field mold parts, which are moved in the closedstate, together with the support core, which has been inserted into thebristle field cavity and has preferably already been fixed by way of thefixing element, can be moved to the handle mold parts in such a mannerthat the bristle field cavity opening and the handle cavity opening areconnected together and the bristle field cavity together with the handlecavity, where applicable with the neck cavity, realize an injectioncavity.

In a preferred manner, a hot channel for supplying the liquefiedplastics material into the injection cavity opens out into the handlecavity. The injection point formed as a result preferably lies in thehandle of the interdental brush.

The bristle field mold parts can define more than one bristle cavity,each with a bristle field cavity opening. This is the case in particularwhen two interacting bristle field mold parts suffice.

A wire, in particular a steel wire, is preferably used a the supportcore. The diameter of the support core is between 0.1 mm and 0.4 mm andpreferably between 0.15 mm and 0.25 mm. The length of the support core,dependent on the length of the bristle-carrying stem, is between 5 mmand 25 mm and is preferably between 13 mm and 20 mm.

The length of the support core is preferably chosen such that thesupport core ends where the cap-like extension of the bristle-carryingstem starts. However, it is also possible to develop the length of thesupport core such that a uniform surface layer is formed over the entiresupport core.

The support core is preferably realized as a straight cylinder. In thiscase, the cross section is preferably round, however, it is alsopossible to shape the cross section as a regular n-angle form or to giveit a T-shaped or double T-shaped profile or to define another closedcontour as a cross section. The important point is that the support coreis able to be introduced into the closed bristle field cavity withoutany problems.

In principle, the support core can also be realized in a form that isnot straight but curved so long as it is able to be inserted into theclosed bristle field cavity. For example, a banana shape would bepossible. As, however, the insertion of the support core is moredifficult, it is simpler to introduce possible curvatures of thebristle-carrying stem after the injection molding.

In the region of the fixing of the support core, it is also possible togive the support core a structure which improves the fixing. Forexample, a snake shape or a helix, short forms which improve theclamping of the support core interacting with the fixing element whichis adapted if needs be.

The casing is realized in such a manner that it overlaps the exposed endof the support core in a cap-like manner. The steel wire which is usedin a preferred manner is thus not on the surface.

In a preferred manner, the support core and consequently the wireprotrudes by between 3 mm and 12 mm, preferably by between 4 mm and 6mm, beyond the bristle-carrying stem in the direction of the handle, ina preferred manner right into the neck portion.

On the side of the fixing element remote from the bristle-carrying stem(after the fixing element), the length of the support core or steel wireis between 0.5 mm and 3 mm and preferably between 1 mm and 2 mm.

Plastics material, for example PA or POM, or materials such as Keflarcan be used for the support core along with the already named metal. Ingeneral, materials which ensure good restoring torque and do not breakwhen bent multiple times are suitable.

The support core can comprise a special surface structure or surfacetreatment.

A smooth surface promotes sliding and can exert a negative influence as,depending on the material combination, the support core can break out ofthe casing because a relative movement is possible between the twoelements. If the surface is roughened, for example, the adhesion betweenthe plastics material and the support core material can be improved. Therough structure can be improved in general by etching, insertion ofstriations or structure.

In order to achieve a roughness, it is also possible to coat the surfaceof the support core in a corresponding manner. Varnish, adhesionpromoting agent or primer are suitable for this purpose. The importantpoint in this connection is that the surface coating is not pushed awayby the injection pressure or damaged in the process on account of theheat.

The thickness of the casing (measured in the radial direction outsidethe region of the bristles and with reference to the longitudinaldirection) is between 0.05 mm and 0.3 mm and is preferably between 0.1mm and 0.2 mm.

In a preferred manner, the diameter of the bristle-carrying stem, i.e.the diameter without bristles, is between 0.2 mm and 1.5 mm and in apreferred manner is between 0.35 mm and 0.9 mm.

In a preferred manner, the bristle-carrying stem comprises a length ofbetween 6 mm and 16 mm and in a particularly preferred manner of between9 mm and 13 mm.

In a particularly preferred manner, the bristle-carrying stem comprisesa conical outside surface. At the exposed end of the support core, thediameter is preferably between 0.35 mm and 0.65 mm, at the handle end ofthe bristle-carrying stem it is preferably between 0.65 mm and 0.85 mm.

The bristles, measured from the casing to the exposed end, in apreferred manner comprise a length of between 0.2 mm and 5 mm and in aparticularly preferred manner of between 0.5 mm and 3 mm.

The ratio between the bristle diameter and the diameter of the supportcore is between 1:8 and 3:1 and is preferably between 1:2 and 3:4.

The ratio between the bristle diameter and the diameter of thebristle-carrying stem is between 1:30 and 3:2 and is preferably between1:6 and 1:3.

The shell created by the bristle field (on the ends of the bristles) canassume the most varied forms. For example, the bristles can form astraight circular cylinder or a cylinder with a triangular cross section(form of a Xmas tree). In addition, other forms where the cross sectionchanges over the length or said cross section is not regular at a pointare also possible. Thus, wave-shaped or comical forms can be provided.Molds as can be achieved in the case of screwed-in brushes, can also berealized in this way, and there are more possibilities provided from theviewpoint of complexity as the boundaries are set just by the injectionmold.

The diameter of the bristles, in a preferred manner, is between 0.05 mmand 0.3 mm and in a particularly preferred manner between 0.1 mm and 0.2mm—measured at the bristle stem which is realized so as to be roundedoff in a preferred manner at the exposed end.

In a preferred manner, the bristles are arranged in between 2 and 10, ina particularly preferred manner between 4 and 8, in particular 6 rows ofbristles which extend in the longitudinal direction and are evenlydistributed in the circumferential direction.

In addition, in a preferred manner the bristles are arranged in planes,so-called bristle planes, which extend at right angles to thelongitudinal direction and are arranged spaced apart at a preferablyconstant distance in the longitudinal direction. It is also possible toarrange the bristle planes in a non-regular manner, i.e. to vary thedistances they are spaced apart.

An angle of preferably 45°, 60° or 90°, which is regular over the entirecross section of the bristle field on account of the preferably regulararrangement of the rows of bristles, is realized between thelongitudinal central planes which are defined by the bristles. Anirregular arrangement, i.e. different angles between the rows ofbristles, is possible.

The distance between adjacent bristles, measured in the longitudinaldirection and along the connecting line from bristle center to bristlecenter between the bristles, is preferably between 0.2 mm and 0.8 mm, inparticular between 0.4 mm and 0.6 mm.

In a preferred manner, between 10 and 40, in particular between 18 and30 bristles are provided in one bristle row. Between 200 and 400bristles and preferably between 100 and 150 bristles are arranged in theentire bristle field in this way.

The outside diameter of the bristle field is preferably between 1 mm and6 mm, and in a particularly preferred manner between 1.5 mm and 4 mm.

The dimensions for the bristle field, which is formed by the bristlefield mold parts, are also obviously produced from the specifieddimensions for the casing and the bristles.

The parting plane of the bristle field mold parts extends in a preferredmanner through the bristles of at least one row of bristles. If fourrows of bristles are provided, the parting plane, in a preferred manner,extends through the bristles of two rows of bristles which are locateddiametrically opposite one another. In a particularly preferred manner,each row of bristles has associated therewith a parting plane, inparticular in the event of there being provided more than two bristlefield mold parts. This implies simpler production, provides theinjection mold with sufficient ventilation possibilities for thebristles and finally the bristle lengths and diameters are notrestricted by the production method of the injection mold.

In a preferred manner, the clamping punches are realized in acircular-cylindrical manner and comprise a diameter of between 0.75 mmand 3 mm, in a particularly preferred manner of between 1.2 mm and 1.8mm. Said diameter also corresponds to the diameter of the recess formedby the clamping punches or of the passage in the neck region.

Further alternative cross sections are, for example, oval or n-angleforms. The round forms have the advantage for reasons of the fluidhandling of the plastics material.

In a preferred manner, the clamping punches, on their end regions thatface one another, comprise teeth or clamping prongs with a height ofbetween 0.4 mm and 2 mm and in a preferred manner between 0.6 mm and 0.9mm (said height is measured from the longitudinal axis).

With reference to the longitudinal direction, in a preferred manner onetooth is provided on the one side and two teeth are provided on theother side. The other clamping punch is realized in the oppositedirection such that the teeth engage in a meshing manner with oneanother in the clamping position. There can also be more than threeteeth present per clamping punch.

It is also conceivable for the one clamping punch to comprise twooppositely situated teeth which engage in corresponding tooth spacesbetween each of the two teeth of the other clamping punch.

The length of the fixing of the support core by the clamping punch oranother fixing element is between 0.7 mm and 2.5 mm and preferablybetween 1 mm and 2 mm.

In this case, said length is preferably distributed uniformly among thedifferent elements, e.g. teeth, i.e. they have the same widths. As analternative to this, it is also possible to vary the widths.

In a preferred manner, the position of the fixing elements is chosensuch that the distance from the fixing element to the beginning of thebristle-carrying stem is between 1 mm and 6 mm and is preferably between3 mm and 5 mm.

It is also conceivable to apply a two-component or multiple-componentinjection molding method. In this case, it is possible, for example, toproduce the layer or the casing and the bristles from one plasticsmaterial and the handle part from another plastics material. Inaddition, it is also possible to produce the casing and the bristles aswell as part of the handle from one plastics material and to manufacturethe remaining part of the handle part as a result of injecting on asecond plastics material. The second plastics material can also coverexposed parts of the support core.

Different plastics materials can be used for realizing the brush, inparticular the interdental brush. The materials specified below can beused for a possible plastics material support core, the bristle fieldand the casing or the handle part. Plastics materials which enter into amaterial bond together by means of multiple-component injection moldingare used in a preferred manner.

A plastics material support core is produced from a harder plasticsmaterial than the plastics material for the bristle field and the layeror casing or the handle part.

The following hard components are possibilities of examples from thearea of thermoplastics:

-   -   styrene polymerisats such as styrene acrylonitrile (SAN),        polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), styrene        methyl methacrylate (SMMA) or styrene butadiene (SB);    -   polyolefins such as polypropylene (PP) or polyethylene (PE) for        example also in the forms of high density polyethylene (HDPE) or        low density polyethylene (LDPE);    -   polyesters such as polyethylene terephthalate (PET) in the form        of acid-modified polyethylene terephthalate (PETA) or        glycol-modified polyethylene terephthalate (PETG), polybutylene        terephthalate (PBT), acid-modified polycyclohexylene dimethylene        terephthalate (PCT-A) or glycol-modified polycyclohexylene        dimethylene terephthalate (PCT-G);    -   cellulose derivatives such as cellulose acetate (CA), cellulose        acetate butyrate (CAB), cellulose propionate (CP), cellulose        acetate phthalate (CAP) or cellulose butyrate (CB);    -   polyamide (PA) such as PA 6.6, PA 6.10 or PA 6.12;    -   polymethyl methacrylate (PMMA);    -   polycarbonate (PC);    -   polyoxymethylene (POM);    -   polyvinyl chloride (PVC);    -   polyurethane (PUR).

The following soft components are examples from the range ofthermoplastic elastomers (TPE's):

-   -   thermoplastic polyurethane elastomers (TPE-U)    -   thermoplastic styrene elastomers (TPE-S) such as, for example, a        styrene ethylene butylene styrene copolymer (SEBS) or styrene        butadiene styrene copolymer (SBS)    -   thermoplastic polyamide elastomers (TPE-A)    -   thermoplastic polyolefin elastomers (TPE-O)    -   thermoplastic polyester elastomers (TPE-E).

In addition, the thermoplasts polyethylene (PE) and polyurethane (PU) asnamed can be used both as hard components and as soft components.

An ethylene vinyl acetate (EVA) can be used in particular as apolyolefin.

PP is particularly suited as a hard component, most preferred is PP witha modulus of elasticity of between 1000 and 2400 N/mm², preferablybetween 1300 and 1800 N/mm². In a preferred manner a TPE-S is used as asoft component. The Shore A hardnesses of the soft components arepreferably below 90 Shore A. The soft components form a material bondwith the hard component by means of over injection using thetwo-component or multiple-component injection molding method.

Example materials for the production of injected bristles:

-   -   polyamide elastomers (e.g. Grilflex ELG 5930 of Ems-Chemie AG)    -   polyester elastomers (e.g. Riteflex 672 RF Nat or Riteflex RKX        193 RF Nat of Ticona Polymers or Hytrel 7248 of Dupont)    -   thermoplastic polyurethane elastomers (e.g. Desmopan DP 1092A,        DP 3065D, DP 1092A of Bayer Material Science or Elastolan 1154        D, 1195 A of BASF).

The bristle materials have a Shore D hardness of between 0 and 100,preferably of between 30 and 80 and in a particularly preferred mannerof between 50 and 70.

So-called bioplastics materials, plastics materials which are producedfrom renewable raw materials, can also be used.

It is also possible, in particular, to produce mascara brushes using themethod and an injection mold of this type. In the case of said mascarabrushes, the length of the bristle field is between 8 mm and 30 mm,preferably between 8 mm and 15 mm or between 22 mm and 28 mm. Thebristles comprise a length of between 1.5 mm and 3 mm. All remainingdimensions can correspond to those of the interdental brush.

It is equally conceivable to produce treatment heads of electricallyoperated interdental cleaners (toothbrushes) or of ear cleaners, pipecleaners, bottle brushes and applicator brushes (medical area) in thisway.

The support cores are preferably inserted into the bristle field cavityby means of a feed and supply device. Said device can comprise, forexample, a hopper with support cores which are separated into singlesand then pushed forward into the bristle field cavity, or a cuttingdevice which detaches from a long store portions which form supportcores and which are supplied to the bristle field cavity.

As an alternative, the support cores are produced in an upstream orintegrated inject mold. A multiple-component injection mold can be used.

The invention is explained in more detail by way of an exemplaryembodiment shown in the drawing, in which, in a purely schematic manner:

FIG. 1 shows a perspective representation of an interdental brush;

FIG. 2 shows a view from the front of the interdental brush of FIG. 1 ;

FIG. 3 shows a top view of the interdental brush of FIG. 1 ;

FIG. 4 shows a view from the rear of the interdental brush of FIG. 1 ;

FIG. 5 shows a bottom view of the interdental brush from FIG. 1 ;

FIG. 6 shows a side view in the direction of the arrow VI of FIG. 2 ofthe bristle trimming of the interdental brush shown in FIGS. 1 to 5 ;

FIG. 7 shows the same representation as FIG. 2 , but in an enlargedmanner, of part of the interdental brush with the bristle trimming;

FIG. 8 shows a top view, and in an enlarged manner compared to FIG. 3 ,of the same part of the interdental brush as FIG. 7 ;

FIG. 9 shows a cross section of the interdental brush between twobristle planes along the line IX-IX of FIG. 8 ;

FIG. 10 shows a cross section of the interdental brush in a bristleplane along the line X-X of FIG. 8 ;

FIG. 11 shows a longitudinal section of the interdental brush along theline XI-XI of FIG. 7 ;

FIG. 12 shows a plan view, highly simplified, of a first part of theinjection mold in the closed state and a second part of the injectionmold with an open handle cavity and an injected handle of an interdentalbrush located therein;

FIG. 13 shows a longitudinal section through the injection mold alongthe line XIII-XIII of FIG. 12 with an interdental brush producedtherein, wherein the second mold part is shown in a part open positionand the first mold part in its closed position;

FIG. 14 shows a cross section through the first part of the injectionmold which is in the closed state with an interdental brush in a bristleplane along the line XIV-XIV of FIG. 13 ;

FIG. 15 shows a perspective representation of part of the first moldpart with a bristle field cavity and a support core introduced into saidbristle field cavity;

FIG. 16 shows the same representation as FIG. 15 of part of the firstmold part with an interdental brush injected therein;

FIG. 17 shows a perspective representation of part of the first moldpart in the open state in a further embodiment;

FIG. 18 shows the same representation as FIG. 17 of part of the firstmold part also in the open state but with an interdental brush producedtherein;

FIG. 19 a shows a perspective representation of a first clamping punchfor securing the support core in the injection mold;

FIG. 19 b shows a second clamping punch, the free end region of which isformed in a mirror-inverted manner to the first clamping punch shown inFIG. 19 a;

FIG. 20 shows a sectional and schematic view of the injection mold;

FIG. 21 shows a flow diagram for producing the interdental brushaccording to the invention;

FIG. 22 shows a simplified sequence for possible further processing ofthe interdental brush produced using injection molding;

FIG. 23 shows a perspective representation of an embodiment of aninterdental brush according to the invention;

FIG. 24 shows a view from the front of the interdental brush of FIG. 23;

FIG. 25 shows a view from the rear of the interdental brush of FIG. 23 ;

FIG. 26 shows a side view of the interdental brush of FIG. 23 ;

FIG. 27 shows a frontal view of the interdental brush of FIG. 23 ;

FIG. 28 shows a cross section of the interdental brush from FIG. 23between bristle planes;

FIG. 29 shows a cross section of the interdental brush from FIG. 23between bristle planes in a further development variant of thecombination of support core/casing or layer;

FIG. 30 shows a view from the front of a product group of interdentalbrushes according to FIGS. 23-29 ;

FIG. 31 shows a view from the rear of the product group of interdentalbrushes according to FIGS. 23-29 ;

FIG. 32 shows a view from the front of a further embodiment of aninterdental brush according to the invention;

FIG. 33 shows a view from the rear of the interdental brush according toFIG. 32 ;

FIG. 34 shows a side view of the interdental brush according to FIG. 32;

FIG. 35 shows a view from the rear of a product group of interdentalbrushes according to FIG. 32 ;

FIG. 36 shows a view from the front of a product group of interdentalbrushes according to FIG. 32 ;

FIG. 37 shows a frontal view of the connecting group of interdentalbrushes according to FIG. 32 ;

FIG. 38 shows a view from the front of a further embodiment aninterdental brush according to the invention;

FIG. 39 shows a view from the rear of the interdental brush according toFIG. 38 ;

FIG. 40 shows a side view from of the interdental brush according toFIG. 38 ;

FIG. 41 shows a frontal view of the interdental brush according to FIG.38 ;

FIG. 42 shows a view from the rear of a product group of interdentalbrushes similar to FIGS. 38-40 ;

FIG. 43 shows a view from the front of the product group of interdentalbrushes similar to FIGS. 38-40 ;

FIG. 44 shows a view from the front of a further embodiment of aninterdental brush with the wire having been injection coated;

FIG. 45 shows a side view of the interdental brush according to FIG. 44;

FIG. 46 shows a view from the front of a preferred embodiment of aninterdental brush with the wire having been injection coated.

The interdental brush 10 shown in FIGS. 1 to 11 comprises a bristlefield portion 12, a neck portion 14 and a handle portion 16 with ahandle 16′. A bristle-carrying stem 18, from which bristles 20 protrude,extends, in the present case in a straight line, over the entire lengthof the bristle field portion 12 and establishes a longitudinal direction22; the dot-dash line showing the longitudinal direction 22 also definesthe longitudinal axis.

As can be seen in particular in FIGS. 9 to 11 , an elongated supportcore 24, which is formed by a spring steel wire in the exemplaryembodiment shown, extends in the interior of the bristle-carrying stem18 and coaxially with respect to the longitudinal axis 22. It extendsover the length of the bristle field 26 formed by the bristles 20 andover the neck portion 14. The support core 24, in the region of thebristle field 26, supports a layer 28 which forms a casing 28 here whichsurrounds the free end of the bristle support core 24 remote from theneck portion 14 by way of a cap-like extension 30. The casing 28 isrealized in such a manner that when the interdental brush is used thesupport core 20 is not able to come into contact with the teeth or thegum. In this case, the cap-like extension 30 is preferably realizedconnecting to the casing 28 in a continuous manner.

The casing 28 and the bristles 20 are produced using the injectionmolding method from the same plastics material component from which—inthe present case—the handle portion 16 and, in the neck portion 14 whichconnects the bristle field portion 12 to the handle portion 16, the neckshell 32 which surrounds the support core 24 are injected. The casing 28with the extension 30, the bristles 20, the neck shell 32 and the handleportion 16 which forms the handle 16′ are realized integrally with oneanother and are formed in one single injection molding step.

It is obviously possible, in a two-component or multiple-componentinjection molding method, for example to realize the bristle fieldportion 12 and the neck portion 14 with a first plastics materialcomponent in order to form the handle portion 18 with a second plasticsmaterial component or, for example, in the handle portion to inject asecond component, for example a soft component, onto the part of thehandle 16′ formed by the first component in order to improve the grip.

The bristle-carrying stem 18 is realized widening in a (slightly)conical manner from the extension 30 up to the start of the neck portion14.

The bristles 20 are arranged in bristle rows 34—in the exemplaryembodiment shown there are six rows of bristles 34—which extend in thelongitudinal direction 22 and in a radial manner and are uniformlydistributed in the circumferential direction. In addition, the bristlesare situated in bristle planes 36 which extend at right angles to thelongitudinal direction 22 and are arranged spaced apart from one anotherin the longitudinal direction 22. In each case one bristle 20 of eachbristle row 34 is situated in each of the bristle planes 36. For thesake of better clarity, the rows of bristles are only shown in FIG. 6 byway of the reference 34 and two bristle planes 36 are only shown in FIG.8 ; there are twenty two bristle planes 36 in the exemplary embodimentshown.

The casing 28 comprises—in the exemplary embodiment shown—grooves, whichextend in a straight-line always centrally in each case between twoadjacent bristle planes 36 and at right angles to the longitudinaldirection, define support points 38 and are at least approximatelyalmost semicircular in cross section, said support points 38 beingarranged from space to space in each case between two bristle planes 36offset by 90° in a direction of rotation.

A thin layer, a film of the plastics material, is situated between thebottom of said grooves and the support core 24. However, it is alsoconceivable for the support core to be exposed at the bottom of thesupport points 38. However, it cannot come into contact with the teethor the gum on account of the casing 28.

As further shown from the figures, the free ends of the bristles 20 liealong the outside surface of an imagined cone which widens (slightly)from the free end of the bristle field 26 in the direction of the neckportion 14 and the axis of which coincides with the longitudinal axis22.

In the exemplary embodiment shown, the bristles 20 are circular in crosssection and are realized tapering conically outward in the radialdirection, the ends of the bristles being realized in a rounded manner,in this case in a hemispherical manner.

The cone angle in this connection is between 1° and 2°. Other crosssections for the bristles 20 are obviously possible and the ability ofthe bristles 20 to be removed from the mold in the injection moldingprocess sets the limits in this connection.

Preferred dimensions for the bristle-carrying stem 18, the bristles 20,the support core 24, the casing 28 and the realization of the bristlefield 26 are specified in the introduction.

It is also conceivable to realize the bristle-carrying stem 18 in acylindrical manner, in particular in a circular-cylindrical mannerand/or to arrange the free ends of the bristles 20 in the shell of animagined circular cylinder which is concentric to the longitudinal axis22, or, as is shown in conjunction with FIGS. 15 to 18 , to provide themin the outside surfaces of two oppositely directed cones. Other formsare also possible.

The casing 28 merges continuously into the neck shell in the neckportion 14, where the outside cross section of the neck portion 14widens continuously in the direction of the handle portion 16. Inaddition, the casing 28 in the free end region of the interdental brush10 merges continuously into the cap-like extension 30.

The neck shell 32 comprises a passage 40 which extends at right anglesto the longitudinal direction 22 and, in the present case, iscircular-cylindrical and through the center of which the support core 24extends. Said support core is visible from the outside. In a preferredmanner, the handle end of the support core 24 does not lie in thepassage 40 but rather an end portion of the support core 24 extends fromthe passage 40 in the direction toward the handle portion into theplastics material, from which the handle 16′, the neck shell 32, thecasing 28 with the extension 30 and the bristles 20 are produced; thisis shown in particular in FIG. 11 .

In the exemplary embodiment shown, the size of the handle portion 16 orof the handle 16′ is that of a fingertip such that it can easily be heldby the thumb and forefinger. Obviously, the handle portion 16 or thehandle 16′ can be given an arbitrary other form, in particular it can berealized in a longer manner.

FIGS. 12 to 14 show a highly simplified representation of an embodimentof an injection mold 42 for producing the interdental brush shown inFIGS. 1 to 11 .

The injection mold 42 comprises a first mold part 44 for producing thebristle field portion 12 and the neck portion 14 as well as a secondmold part 46 for producing the handle portion 16.

The first mold part 44, in the exemplary embodiment shown, is providedwith six bristle field mold parts 48 which, in the closed state, definea bristle field cavity 50 for producing the casing 28, the bristles 20and the cap-like extension 30. On an end face 52—this is facing a neckmold part 56 and consequently the second mold part 46—the bristle fieldcavity 50 comprises a bristle field cavity opening 54.

In addition, the first mold part 44 has associated therewith the twoneck mold parts 56 which are realized in a beam-like manner and—in theclosed state—define a neck cavity 58. On the side facing the bristlefield cavity 50, the neck cavity 58 comprises a first neck cavityopening 60 which—in the closed state of the injection mold 42—isarranged at the bristle field cavity opening 54 and is aligned with thesame; the neck mold parts 56 abut against the end face 52. In addition,on the side remote from the bristle field cavity 50 and facing thesecond mold part 46, the neck cavity 58 comprises a second neck cavityopening 62.

In addition, each of the neck mold parts 56 has associated therewith aclamping punch 64. With reference to the longitudinal direction 22 whichis defined by the bristle field cavity 50, the clamping punches 64 arelocated radially opposite one another and are movable along a straightline, which extends at right angles to the longitudinal axis 22 andintersects it, from a rest position in which they are spaced apart fromone another, toward one another into a clamping position which is shownin FIG. 13 ; said mobility is shown by double arrows.

The clamping punches 64 together form a fixing element 64′ for fixingthe support core 24.

The second mold part 46 comprises two handle mold parts which realize ahandle cavity 68 in the closed state. For the sake of better clarity,only one of the handle mold parts 66 is shown in FIGS. 12 and 13 .

On a side facing the neck cavity 58, the handle cavity 68 comprises ahandle cavity opening 70 which—in the closed state of the injectionmold—is arranged abutting against the second neck cavity 62 and is inalignment with the same.

In the closed state of the injection mold 42, the bristle field cavity50, the neck cavity 58 and the handle cavity 68 together form aninjection cavity 72.

As this is generally known and also proceeds from the interdental brush10 shown in FIGS. 13 and 14 , the bristle field cavity 50 is realizedcorresponding to the bristle field portion 12 of the interdental brush10, the neck cavity 59 is realized corresponding to the neck portion 14of the interdental brush 10 and the handle cavity 68 is realizedcorresponding to the handle portion 16 of the interdental brush 10. Thedimensions of said cavities 50, 58, 68 consequently also proceed fromthe dimensions of the interdental brush 10 specified in theintroduction. The forms of the cavities 50, 58 and 68 are produced fromthe interdental brush 10 shown in the figures.

As this can be seen in particular from FIG. 13 , which also shows aninterdental brush 10 produced in the injection mold 42 with the secondmold part 46 open on one side, the support core 24 is held during theinjection molding of the plastics material in a clamping manner by meansof the clamping punches 64 which form the fixing element 64′.

If the plastics material is injected into the handle cavity 68, it flowsthough the neck cavity 58 into the bristle field cavity 50 without thesupport core 24 being able to be displaced in the longitudinal direction22.

Over and above this, support elements 74, which are realized on bristlefield mold parts 48 and correspond in a mirror-inverted manner to thesupport points 38 described in conjunction with the description of theinterdental brush 10, are shown in FIG. 13 . The support elements 74protrude in the direction toward the interior of the bristle fieldcavity 50 and thus form the support points 38.

As can additionally be understood from FIG. 13 , in the closed state ofthe injection mold 42 the bristle field cavity 50 merges continuouslyinto the neck cavity 58 and said neck cavity merges continuously intothe handle cavity 68 and they thus form the injection cavity 72.Obviously it is conceivable to realize steps, groove or channels at saidtransition points.

As can be seen from FIG. 14 , the parting planes 76 of the bristle fieldmold parts 48 coincide with the longitudinal center planes 78 of therows of bristles 34.

Over and above this, FIG. 14 shows the bristles 20 which are arranged inone of the bristle planes 36 and are produced integrally with the casing28 of the support core 24 using the injection molding method.

In conjunction with FIGS. 12 to 14 , the main features of the method canalready be discussed.

The bristle field mold parts 48, in the exemplary embodiment shown, aretransferred into the closed state of the first mold part 44 in theradial direction relating to the longitudinal direction 22, after whichthey form the bristle field cavity 54 which comprises the bristle fieldcavity opening 54 at the end face 52. The support core 24 (arranged inthe longitudinal direction) is then inserted in the longitudinaldirection 22 through the bristle field cavity opening 54 into thebristle field cavity 50 and is then held in situ by means of theclamping punches 64.

In this case, either the support core 24 is inserted the first into theneck mold part 56 and clamped and then, as result of moving the neckmold part 56 to the end face 52 of the bristle field mold parts 48, isinserted into the bristle field cavity 50 or the neck mold part 56 ismoved to the bristle field cavity 50, the support core 24 is moved rightthrough the neck mold part 56 into the bristle field cavity 50 and isthen clamped.

As a result of injecting plastics material into the bristle field cavity50, the casing 28 and consequently in an integral manner the bristles 20are realized.

The plastics material is moved through the bristle field cavity opening54 into the bristle field cavity 50.

In the exemplary embodiment shown, the support core 24 is held centrallyin the bristle field cavity 50 by means of the support elements 74 whichare distributed in the circumferential direction and in the longitudinaldirection.

In the exemplary embodiment shown, the clamping punches 64 areassociated with the neck mold parts 56 which—in the closed state—definethe neck cavity 58 which is connected to the bristle field cavity 50.Consequently, the neck shell 32 is also injected simultaneously andintegrally with the casing 28 and the bristles 20.

In this case, the plastics material flows around the clamping punches 64and the passage 40 is realized in the neck shell 32.

In addition, in the exemplary embodiment shown, a handle 16′ of theinterdental brush 10 is also formed. To this end, the first mold part 44with the support core 24, which is inserted into the bristle fieldcavity 50 and is held fast by means of the clamping punches 64, is movedto the second mold part 46 such that the second neck cavity opening 62comes to lie at the handle cavity opening 70. With the handle mold parts66 situated in the closed position and the handle cavity 68 consequentlyclosed, the plastics material is injected into said handle cavity 68which passes through the neck cavity 58 also into the bristle fieldcavity 50.

For removal from the mold, the handle cavity 68 is initially opened as aresult of lifting the handle mold parts 66 off one another. The handle16′ is then removed out of the region of the handle cavity 68 by thefirst mold part 44 and the second mold part 46 being moved away from oneanother. After moving the clamping punches 64 from the clamping positionin the radial direction outside the neck cavity 58 and opening the neckcavity 58 by moving the neck mold parts 56 away from one another as wellas opening the bristle field cavity 50 as a result of moving the bristlefield mold parts 48 away from one another in the radial direction, theinterdental brush 10 is completely removed out of the mold.

FIGS. 15 to 18 shows perspective representations of the first mold part44 for producing interdental brushes, as have been shown in theremaining figures and described further above. The difference to thefigures already shown and described from the point of view mold designis that the cap-like extension 30 is molded in a separate part of thefirst mold part 44—in a cap mold part 80. Said mold part would bevisible in FIGS. 15 and 16 , but is not shown for reasons of clarity.

The differences on the product side are in the realization of thebristle field 26 and in the shape of the handle 16′. All the bristles 20are, once again, arranged in six rows 34 of bristles which aredistributed uniformly in the circumferential direction and all thebristles 20 are situated in bristle planes 36 which are arranged at aconstant spacing from one another in the longitudinal direction 22. Abristle 20 of each row 34 of bristles is situated in each bristle plane36. However, the free ends of the bristles 20 are no longer situated onone single conical outside surface, but rather they end in twooppositely directed conical outside surfaces which, with their smallerdiameter, proceed from the axial ends of the bristle field 26 and meetat least approximately in the center.

Obviously, other realizations of the bristle field 26 with the injectionmold 42 shown are also possible, as is also the one shown in FIGS. 1 to11 ; only the bristle field cavity 50 has to be realized in acorresponding manner.

In addition, as can be seen in FIGS. 16 to 18 , the handle 16′ isrealized in a cuboid manner with rounded edges. The handle cavity 68,which is formed by the second mold part 46, is molded in a correspondingmanner. Otherwise the realization is the same as discussed inconjunction with FIGS. 12 to 14 .

FIG. 15 shows a perspective representation of three of the six bristlefield mold parts 48 which are situated in the closed state. Theremaining three bristle field mold parts 48 and also the cap mold part80 are not shown in order to make it possible to see into the interiorof the injection mold 42. In addition, FIG. 15 shows one of the twobeam-like neck mold parts 56 which, in the closed position of the secondmold part 46, abuts in the axial direction against the bristle fieldmold parts 48, i.e. against the end face 52, in such a manner that thebristle field cavity opening 54 lies at the first neck cavity opening60. In addition, FIG. 15 shows the one half of the neck cavity 58 intowhich protrudes the clamping punch 64 which is associated with said neckmold part 56. The two neck mold parts 56 (apart from the clampingpunches) are formed in a mirror-inverted manner at least at theinterface and in the closed state of the injection mold 42 define theneck cavity 58. Mirror-inverted molding is advantageous in order toenable uniform filling when introducing the plastics material in theinjection molding process.

The cap mold part 80, which, when the plastics material is injected,forms a cap cavity 82 for forming the extension 30 which covers the freeend of the support core 24, abuts against the bristle field mold parts48 on the side of said bristle field mold parts remote from the neckmold part 56; see also FIGS. 1 to 11 . The cap mold part 80 or the capcavity 82 are preferably formed in one part. This means that the capcavity 82 is developed as a blind hole and removal from the mold ispossible only in the longitudinal direction 22. Consequently, said partis moved away from the bristle field mold parts 48 in the longitudinaldirection 22 in the process before the bristle field 26 can be moved outof the remaining first mold part 44.

In addition, FIG. 15 shows the support core 24 which has been insertedin the longitudinal direction 222 through the neck cavity 58 and thebristle field cavity opening 54 into the bristle field cavity 50 oncethe bristle field mold parts 48 have been transferred into the closedstate.

In addition, FIG. 16 shows dovetail-like guide slots 96 for the bristlefield mold parts 48. The associated radial guides 84 are realized on asupport body 86, the design of which can also be seen in FIGS. 17 and 18.

It must be mentioned just for the sake of completeness that the partingplanes 76 once again lie in the longitudinal center planes 78 of thebristle rows 34. In addition, bristle field mold parts 48 comprisesupport elements 74 (compare FIG. 14 ) which serve for centering thesupport core 24 in the bristle field cavity 50.

FIG. 16 shows the same representation as FIG. 15 of an interdental brush10 produced in the injection mold 42. In the passage 40, which is keptfree of plastics material during injection molding by the two clampingpunches 64, in the neck shell 32 it is possible to see, on the one hand,the exposed fixing portion 88 of the support core 24 (see also FIGS. 2,4, 7, 11 and 14 ) and, on the other hand, the one clamping punch 64which is still shown in the clamping position.

FIG. 17 shows the first mold part 44 in the open state. Theroller-shaped support body 86 comprises (on the end face 52) an endplane 90 which extends at right angles to the longitudinal direction andfaces the neck mold parts 56. The support body 86 comprises in thepresent example six guide grooves 92 which, with reference to thelongitudinal direction 22 extend in the radial direction, aredistributed uniformly in the circumferential direction and are open inthe end plane 90. A bristle field mold part 48, which is mounted thereinso as to be displaceable in the radial direction, is inserted into eachof said guide grooves 92.

In FIGS. 15 and 16 (not shown in the figures) the side faces of theguide grooves 92, which abut against the side faces 94 of the bristlefield mold parts 48, are provided with dovetail-like radial guides 84.It must be mentioned just for the sake of completeness that obviouslythe bristle-field mold parts 48 comprise correspondinglymirror-invertedly formed guide slots 96 into which the radial guides 84engage. The named guide slots are shown in FIGS. 15 and 16 .

In FIGS. 17 and 18 , the radial guide slots 96 (one guide slot 96 perguide groove 92 and side face 94), which comprise an undercut in adovetail-like manner, are realized from a bottom 98. The correspondinglymirror-invertedly formed radial guides 84 of the support core 86 areguided into said guide slots 96 of the bristle field mold parts 48, eachbristle field mold part 48 comprising two guide slots 96, only one ofwhich is visible in each case in the figures.

In the case of the embodiment (FIGS. 15 to 18 ), the object of thecombinations consisting of guide slots 96 and radial guides 84 is tohold the bristle field mold parts 48 in position in the support body 86in the axial direction with reference to the longitudinal direction 22and to guide then so as to be movable in a translatory manner in theradial direction.

The bristle field mold parts 48 are realized in a cuboid manner, in thecase of the embodiment shown in FIGS. 15 to 18 two oppositely situatedsides (wide sides) in each case being provided with the guide slots 96.

In the end region which is located on the inside in the radialdirection, the bristle field mold parts 48 are formed in a gableroof-like manner, the gables 100 extending in the longitudinal directionand the roof surfaces forming the parting planes 76. This means that inthe closed state the roof surfaces 102 of adjacent bristle field moldparts 48 abut against one another. In the closed state of the bristlefield mold parts, the gables 100 together form that part of the bristlefield cavity 50 which realizes the bristle-carrying stem 18.

Correspondingly groove-like indentations which, in the closed state ofthe bristle field mold parts 48, form the part of the bristle fieldcavity 50 associated with the bristles 29, are realized in the roofsurfaces 102. The roof surfaces 102 thus form part of the bristle fieldcavity 50.

In the end region located radially on the outside, the bristle fieldmold parts 40 comprise dovetail-like guide projections 104 which, intheir imagined extension, enclose an acute angle with the longitudinalaxis 22. The guide projections 104 are guided in mirror-invertedlyrealized sliding grooves of a control ring, which engages around thesupport body 68 and is displaceable back and forth in the axialdirection by means of a drive element. In the one axial end position ofthe control ring, the bristle field mold parts 48 are situated abuttingagainst one another in the closed state and form the bristle fieldcavity 50, as shown in a reduced manner in FIGS. 15 and 16 . In theother end position of the control ring, the bristle field mold parts 48are situated radially on the outside in the open position, as is shownin FIGS. 17 and 18 .

As can be seen in addition from FIGS. 17 and 18 compared to FIGS. 15 and16 , the neck mold parts 56 are mounted so as to be displaceable in thelongitudinal direction 22 relative to the bristle field mold parts 48and also to the support body 86; longitudinal mountings are known ingeneral and are not shown for reasons of better clarity. Drive membersfor the movement of mold parts are known in general and are not showneither.

In FIG. 18 , the first mold part 44 is also situated in the openposition, however in addition, as in FIG. 16 , an interdental brush 10which is produced with the injection mold 42 is shown. Said interdentalbrush is still held by the neck mold parts 56 which are still in theclosed position and of which, however, only one of the neck mold parts56 is shown.

The method of operation of the injection mold 42 is described furtherbelow in conjunction with FIG. 21 .

FIGS. 19 a and 19 b show a preferred embodiment of the two clampingpunches 64 which form a fixing element 64′.

In their end regions 110 which face one another, the clamping punches 64comprise teeth 112 and where applicable molded tooth spaces 114, theteeth 112 engaging into the tooth spaces 114 of the other clamping punch64 in each case in the clamping position.

In the exemplary embodiment shown, the clamping punches comprise acircular profile-shaped cross section, the ends facing one another beingprovided with a punch recess 116 which is v-shaped in cross section andextends in the longitudinal direction 22.

In the bottom of the punch recess 116 the clamping punches 64 comprise achannel 118 each which extends in the longitudinal direction 22, the twochannels, with the clamping punches 64 in the clamping position,corresponding substantially to the outer contour of the support core 24,however being realized in such a manner that in the clamping position ofthe clamping punches 64 the support core 24 is able to be heldclampingly by the channels 118.

In the case of the clamping punch 64 shown in FIG. 19 a , the flanks 120formed by the punch recess 116 are divided centrally in each case intotwo teeth 112 by a transverse recess 122. In the flanks 120, thetransverse recesses 122 form tooth spaces 114 which are formed in amirror-inverted manner with respect to the teeth 112 which are realizedon the clamping punch 64 shown in FIG. 19 b.

In the case of the clamping punch 64 shown in FIG. 19 b , the two flanks120 formed by the punch recess 116 are formed by two transverse recesses122 which are located on the outside in the longitudinal direction 22 toform one tooth 112 each. Said transverse recesses 122 are formed in amirror-inverted manner with respect to the teeth 112 of the clampingpunch 64 shown in FIG. 19 a.

If the two clamping punches 64, which lie in a common axis, are movedtoward one another, the two teeth 112 of the clamping punch 64 shown inFIG. 19 b move into engagement with the tooth spaces 114 of the clampingpunch 64 shown in FIG. 19 a . In a corresponding manner, the four teeth112 of the clamping punch 64 indicated in FIG. 19 a move into engagementwith the outside tooth spaces 114 of the clamping punch 64 shown in FIG.19 b.

In the clamping position, consequently, the support core 24 in thefixing portion 88 is completely surrounded by the clamping punches 64.Over and above this, in the clamping position the two clamping punches64 form a continuous profile which serves for realizing the passage 40during injection molding.

FIG. 20 shows a schematic representation of a possible embodiment of theinjection mold 42 with one single stationarily arranged second mold part46 and four further mold parts 46 which are rotatable about a rotationalaxis 124 and after a rotation are movable in each case about 90° oneafter another to the second mold part 46.

The second mold part 46 comprises the two handle mold parts 66 which, inthe closed state, realize the handle cavity 68. It must be mentioned atthis point that the first mold parts 44 and the second mold part 46 arein each case able to realize several corresponding cavities in order toproduce several interdental brushes simultaneously, as is known ingeneral from toothbrush production.

On the side facing the second mold part 46, each of the first mold parts44 comprises the two neck mold parts 56 which, in the closed state,realize the neck cavity 58 or the neck cavities 58. On the side remotefrom the second mold part 46, each first mold part 44 comprises a capmold part 80 with the corresponding cap cavity or cap cavities 82. Thebristle field mold parts 48 are situated in each case between the neckmold parts 56 and the relevant cap mold part 80. The first mold parts 44are realized as described further above and shown in the precedingfigures. The neck mold parts 56 are movable relative to the bristlefield mold parts 48 in the direction of the double arrowsshown—consequently in the direction of the rotational axis 124 or in thelongitudinal direction 22.

The realization of the injection mold 42 according to FIG. 20 enablesshort cycle times for producing the interdental brushes 10 as each firstmold part 44 assumes four different positions in which differenttreatments are able to be performed in each case, as is shown below inconjunction with FIG. 21 .

In a first position A, the bristle field cavity 50 is closed by thebristle field mold parts 48 being transferred into the closed state. Inaddition, the neck mold parts 56 are moved toward one another into theclosed position and to abut against the bristle field mold parts 48 inthe longitudinal direction 22. The clamping punches 64 or the fixingelement 64′ are held spaced apart from one another in the rest position,outside the neck cavity 58.

Said first mold part 44 is then moved into a second position B—in thecase of the embodiment shown in FIG. 20 as a result of rotating by 90°about the rotational axis 124. In said second position B, the supportcore 24 is inserted through the neck cavity 58 and then the bristlefield cavity opening 54 in the longitudinal direction 22 into the closedbristle field cavity 50, after which the clamping punches 64 are movedtoward one another or the fixing element 64′ is moved into the clampingposition.

The support core 24, in this case, can be supplied to the process as apart which is already present in the correct length (for example a cutpart) or as an endless part. In this case, in the second case it isstill necessary to cut the support core 24 to the correct length in theprocess. In addition, it is also possible to form the support core 24from a plastics material and to do this, for example, in a separate orintegrated injection molding process and in this way an interdentalbrush could be completely manufactured from plastics material.

The first mold part 44 is then moved, once again as a result ofrotation, with the support core 24 inserted and secured therein into athird position C in which the first mold part 44 is situated at thesecond mold part 46. The handle cavity 68 is closed as a result ofmoving the handle mold parts 66 toward one another. In addition, thefirst mold part 44 and the second mold part 46 are moved toward oneanother and into position abutting against one another such that thehandle cavity 68 together with the neck cavity 58 and the bristle fieldcavity 50 including the cap cavity 82 form the injection cavity 72.

The plastics material is then injected into the handle cavity 68, as aresult of which the handle 16′ is realized in the handle cavity 68, theneck shell 32 is realized in the neck cavity 58, the casing 28 and thebristles 20 are realized in the bristle field cavity 58 and theextension 30 is realized in the cap cavity 82.

If the plastics material is hardened at least so that it isdimensionally stable, the handle cavity 68 is opened as a result ofmoving the handle mold parts 66 away from one another. As a result thehandle 16′ is removed from the mold. In addition, the first mold part 44and the second mold part 46 are moved away from one another. The firstmold part 44 is then moved into a fourth position D as a result ofrotation.

In said position D it is possible to inject a second component, forexample from a hard or soft component, on the already produced handle16′. If this is desired, a third mold part of the injection mold 42,which can be realized identically to the second mold part 46, issituated at said fourth position D, however only the cavities next tothe receiving means for the already produced handle 16′ being realizedfor the injecting of the further components.

The already produced handle 16′ protrudes beyond the neck mold parts 56and in the fourth position D passes into the relevant cavity. The moldparts are moved toward one another, the cavity is closed and the secondcomponent is then injected. Once said component has hardened at least inpart, the further handle cavity is opened and the first mold part 44 isthen moved into the first position again, the position A. In saidposition, the bristle field mold parts 48 are transferred into the openstate, as a result of which the bristle field portion 12 and the handleportion 16 of the interdental brush 10 are exposed.

As a result of moving the neck mold parts 56, which are in the closedposition, in the longitudinal direction away from the bristle field moldparts 48, the interdental brush 10 is removed from the bristle fieldcavity 50. The neck mold parts 56 and the clamping punches 64 or thefixing element 64′ are then moved away from one another and beforehand,at the same time or afterwards the clamping punches 64 are transferredinto their rest position. The interdental brushes 10 are free and areable to be removed, for example by means of a gripper (for example on arobot), from the injection mold 42.

Depending on the development, the gripper holds the interdental brushes10 as early as when the neck mold parts 56 and the clamping punches 64are opened. As a further development, it is possible for the producedparts simply to be dropped depending on the design of the injectionmold.

The first mold part 44 is or rather its parts are then closed again asdescribed at the beginning and a new production cycle can start.

The embodiment shown in FIG. 20 with four first mold parts 44 hasconsequently the advantage of a large production capacity, whilst thefirst component of an interdental brush 10 is being injected, treatmentsare being performed in the remaining positions.

If there is no provision for a second component to be injected onto thehandle 16′, the fourth position can be omitted, as is shown in FIG. 21by way of a dotted line. In this case, the injection mold 42 comprisesin an advantageous manner three first mold parts 44 which are rotatedabout the rotational axis 124 from position to position in a preferredmanner by 120° in each case.

In this case, however, it is also possible, for example, to split theactivities of one position into several positions. For example, openingand product removal can be grouped together at position A and separatedfrom closing and moving the mold parts together.

In addition, it is conceivable, as indicated in FIG. 21 by way of thedotted line 126′, to insert the support core 24 into the closed bristlefield cavity 50 in the first position A.

In this case it is advantageous—if no second component has to beinjected onto the handle 16′- to provide two first mold parts 44 whichare rotated in each case about 180° about the rotational axis 124 intothe corresponding positions (A, C). However, if there is provision forthe injecting of a second component, the injection mold 42, in acorrespondingly preferred manner, comprises three first mold parts 44.

In a preferred manner, the first mold parts 44 in each case are arrangeddistributed uniformly in the circumferential direction with respect tothe rotational axis 124 in the manner of the blades of a helicopterrotor.

Details of possible further treatments of the interdental brushes 10produced as described above are provided in conjunction with FIG. 22 .

FIG. 22 shows how the injection molding process and the furtherproduction steps are incorporated into the entire production processwhen a so-called inline solution is used in the production process, i.e.the production steps are linked directly together. The advantagesprovided by said production method are obvious. For example, they areeconomic, no intermediate storage is required and damage to the bristlefield can be quasi ruled out.

For example, it is possible to post-process the injected interdentalbrushes 10 in several steps and then to package them directly. Inaddition, it is possible to provide buffering between the severalprocessing steps. The buffering serves for the purpose of absorbingoscillations in the output between the previous and the subsequentprocess steps.

Thus it is possible for the injected interdental brushes 10 to beprovided, for example, with lettering, for example as a result ofembossing or printing, in a next step after the injection molding. Thepost-processing can also relate to the bristle field, for example theinterdental brush 10 can undergo more bending of the bristle-carryingstem 18. The treatment of the bristle field 26 with substances, forexample dental solutions, toothpaste or antiseptics, is also possible.The influence of heat on the bristle field 26 is also possible as isdistortion of the bristle field 26 so that it obtains a torsion shape.

The named processes are possible prior to or after buffering or alsodirectly prior to the packaging of the interdental brushes 10.

Further processes are also possible inline before the interdentalbrushes 10 are packaged.

It is also conceivable to process the produced interdental brushes 10further offline. To this end, the individual steps can be completelyseparate and take place independently of one another. In this case, itis possible for each intermediate product to be stored before it isprocessed further.

Along with the declared variant that the product is produced completelyin the injection mold and is a stand-alone product, it is also possiblenot to produce the complete product. In this case, it is possible, inplace of the complete handle 16′, to develop an interface geometry whichfits onto a mirror-invertedly formed part of a handle. In this case, thebrush part is exchangeable and is clicked into the handle or fastened inanother manner so as to be releasable again.

In addition, it is also possible to form the interdental brush in asidentical a manner as possible to an existing screwed-in brush, forexample such that a shaft is produced from plastics material using theinjection molding method. The achievement here is that existingscrewed-in brushes without a brush handle can be replaced 1:1. This isused, for example, in handles into which simple screwed-in brushes canbe inserted, the screwed-in brushes being held/clamped as a result ofbending the extension of the bristle-carrying stem.

It is also possible to apply the co-injection method to the productionof the named interdental brushes. This would mean that two componentsare injected for the production in the first cavity of the injectionmold. Specifically, a first component is injected, but it does not fillthe cavity completely. After partial hardening, a second materialcomponent is injected by means of the same injection point such thatsaid component either displaces the existing component in part and takesup space in the interior of the existing component or the additionalcomponent breaks through the existing component. Thus it is possible toproduce a two-component part in one single injection mold cavity. Inthis way, for example, the handle and the bristles can comprisedifferent colors or different materials can be used for the handle andthe bristles.

FIGS. 23 to 29 show a variant of an interdental brush 10 in which thesupport core 24 is also produced from a plastics material using theinjection molding method.

The interdental brush 10 comprises a bristle field portion 12 with abristle field 26, a neck portion 14 with a neck element 32 as well as ahandle portion 16 with a handle 16′. A bristle-carrying stem 18, fromwhich the bristles protrude, extends in the case of this variant also ina straight line over the entire length of the bristle field portion 12and establishes a longitudinal direction 22; the dot-dash linespecifying the longitudinal direction once again defines thelongitudinal axis.

In the present case, the handle 16′, the neck element 32 and the supportcore 24 are injected integrally from a plastics material. The supportcore 24, which connects to the neck element 32 on the side remote fromthe handle 16, comprises a smaller diameter than the neck element 32 andthe support core 24 preferably tapers as the distance between it and theneck 32 increases. A casing 28, which surrounds the free end of thesupport core 24 remote from the neck portion 14, is injected around thesupport core 24.

With regard to as efficient handling as possible, the handle 16′comprises a flattened form. The flattened form can be present, forinstance, in the form of a small plate which, where applicable,comprises trough-shaped indentations on the top and/or bottom surfacefor accommodating finger tips (not shown). Nubs can also be arranged inthe trough-shaped indentations in order to increase the grip further.The bristles 20 are or the bristle field 26 is injected together withthe casing 28. The casing 28 and the bristle field 26, in this case, arepreferably injected from a plastics material other than that of thehandle 16′, the neck element 32 and the support core 24. In addition,for better ergonomics/functionality, the handle 16′ can be provided witha further plastics material component, in particular a soft component.

In the present case, the bristle field 26 consists of bristles 20 whichprotrude substantially from three sides (or from three side portions) ofthe interdental brush 10. One side (or one side portion) remains free ofbristles in the case of this variant. As can be seen, the bristles 20 donot protrude radially from the longitudinal axis 22 of the support core24 in each case, rather the individual rows 34 of bristles, which extendin the longitudinal direction 22, are arranged in each case at leastapproximately parallel or at a 90° angle with respect to one another. Ascan be seen for instance in FIG. 27 , the top three, approximatelyparallel rows 34 of bristles follow the tapering of the support core 24or of the casing 28 (which has a constant thickness uniformly andconsequently extends around the support core 24 also with correspondingtapering) and converge somewhat to a tip whilst the side rows ofbristles protrude perpendicularly from the support core 24 and lie in acommon plane. Obviously other types of angular constellations betweenthe rows 34 of bristles are conceivable in this variant also.

FIG. 29 shows a cross section which is alternative to FIGS. 23-28 in theregion between the rows of bristles. In this case, the support core 24emerges out of the casing in the region of the bristle field portion 12and thus forms at least part of the actual rear side of the bristlefield 26. In this case, therefore, the support core 24 is surrounded bya part casing or layer 28 with the exception of the bottom side.

The support core 24 is developed in a preferred manner in the form of arounded trapeze. The support core can, however, also be developed in atriangular manner and be surrounded by the casing 28 completely on twosides and absolutely not or only in part on one side. The support corecan, however, also comprise a round cross section.

The support core 24 can accordingly also realize a three-dimensionalgeometry which deviates from the preceding embodiments as it is formedtogether with the handle 16′ of the interdental brush 10.

The production of an interdental brush 10 according to FIGS. 23 to 29 issomewhat simpler than that of the preceding embodiments. The supportcore 24 can be produced, for example, in a cavity of an injection moldin which subsequently using the two-component or multiple-componentinjection molding method the bristle field is also produced. In thiscase, as in the preceding embodiments, the support core 24 is insertedin the longitudinal direction 22 through the bristle field cavityopening 54 into the closed bristle field cavity 50. In addition, it isalso possible to produce the support core 24 in a separate injectionmold and to supply it to the injection mold in which the bristle fieldis molded and to insert it correspondingly into the injection moldingcavity.

The fixing of the support core 24 in the injection mold is effected in apreferred manner in the region of the handle 16′, at points at whichonly one plastics material component is present (i.e. in particular notat points at which a soft component is also present for instance).Depending on the development, the fixing can be effected just by meansof the walls of the injection mold cavity—without separate clampingpunches being necessary for this. The fixing element is then formed ineach case by the cavity wall. The injection point 51 of the plasticsmaterial component, which forms the casing 28 as also the bristles 20,is situated in a preferred manner at the front end of the handle 16′. Inthis way, the plastics material component of the casing 28 overlaps asmall part of the surface on the handle 16′, whilst on the rear side ofthe interdental brush 10 on the neck element 14 it covers a substantialpart of the surface of one side before it finally completely covers thesurface in the bristle field portion 26 (cf. FIG. 25 ).

In addition, it is possible to combine the injected bristles 20 withscrewed-in bristles such that, for example, screwed-in bristles arepresent in the front part of the interdental brush 1. To this end, whereapplicable, a screwed-in brush, which comprises screwed-in bristles atits front end and is provided with twisted wire at its rear part, iscreated in a first step. Said part is inserted into the injection moldcavity, clamped and also clamped in front of the region of thescrewed-in bristles. The twisted wire is then injected around andprovided with injected bristles 20.

The product group 200 according to the invention shown in FIGS. 30-31comprises several brushes of the embodiments of the invention shown inFIGS. 23-29 . A product group preferably consists in each case of fivebrushes as shown. As can be seen, the adjacent brushes in this case areconnected together in the region of their handles 16′ by means of twomaterial bridges 128.

The material bridges 128, depending on the development of the handle16′, are the same length or different in length. They can also comprisein each case a predetermined breaking point S, for example in the formof a perforation or an incision or material weakness at which theindividual brushes are able to be separated simply and cleanly from oneanother.

The injection point 51″ of the second component is situated at the frontend of the handle 16′ facing the neck element 32. The second plasticscomponent, in other words, is injected onto the front end of the handle16′ facing the neck element 32, the second plastics material componentoverlapping a small part of the surface on the handle 16′, whilst itcovers a substantial part of the surface on the rear side on the neckelement 32 and covers the surface of the support core 24 completely, orelse with the exception of one bottom side (cf. FIG. 29 ).

The second plastics component is introduced into the product at aseparate injection point 51″ per interdental brush 10. The firstplastics material component is introduced by means of the injectionpoint 51′. In this connection, it is possible for there only to be oneinjection point 51′ of the first component for a product group, or elsefor there to be several injection points 51′. With reference to theirarrangement on the products of the product group, the injection pointsare preferably arranged in a uniform or symmetrical manner. In addition,the injection point 51′ or 51″ is always situated at the same positioninside the individual product. Never more than one injection point ispreferably used per plastics material component per product.

Apart from this, the further structural elements/components correspondto the structural elements/components shown in FIGS. 23-29 . A hotrunner system is regularly used for said embodiment. The use of a coldrunner system is conceivable.

A brush or interdental brush 19 according to the invention which, onceagain, comprises a handle 16′ from which the neck element 32 and thesupport core 24 extend (covered by the layer/casing 28 in this case), isshown in FIGS. 32-34 . As can be seen, three converging rows 34 ofbristles (the center one of which extends along the longitudinal axis22), which define the bristle field 26 together with the two rows 34 ofbristles which protrude substantially horizontally from the support core(or bristle stem 18), are arranged on the top surface of the bristlestem 18.

In this case, the length of the bristles 20 reduces in the direction ofthe end of the bristle stem 18 remote from the neck element 32. As canbe seen in particular also in FIG. 34 , the two rows 34 of bristles,which protrude substantially horizontally from the support core, arearranged in a plane below the longitudinal axis 22 of the support core24.

On account of the fact that, in the present case, the support core aswell as the bristle stem 18 taper in the direction of their end remotefrom the neck element 32, the plane in which lie the rows of bristlesarranged substantially horizontally, is, where applicable, notcompletely parallel to the longitudinal axis 22. The handle 16′ of thebrush, in the present case, is realized in a flat manner. The cap-likeextension 30 of the layer/casing 28 once again surrounds the free end ofthe support core remote from the neck element 32. The injection point51″ for the second plastics material component is situated either at thefree end of the support core or else on the end of the support corefacing the neck element 32 (i.e. in the bristle field cavity opening).No second plastics material component is applied onto the handle 16′ andonto the neck element 32 of the individual brushes. A cold runner systemis regularly used in the case of said embodiment. The injection point51″ lies in a preferred manner at the free end of the support core.

The second plastics material component, as shown in FIGS. 32 and 33 ,may be received in a hole 161 in the handle 16′ where it forms a portionwith increased grip. Different developments are conceivable with regardto embodiments with the hole 161 in the handle 16′. There can be one orseveral holes 161 present, for example there can be one large hole andseveral small holes. The holes 161 are preferably developed in acircular or oval manner, however, n-angle or polygonal holes (withrounded corners for example) are conceivable.

The product group 200′ according to the invention shown correspondinglyin FIGS. 35 and 36 simply comprises a material bridge 128 between thehandles 16′ of the adjacent brushes or interdental brushes 10. Saidmaterial bridges are also formed from the first plastics materialcomponent and can comprise a predefined breaking point S in the form ofa perforation or an incision or a material weakness.

No second plastics material component is applied onto the handle 16′ oronto the neck element 32 of the individual brushes. The connectionbetween the brushes of the product group 200′ by means of the individualmaterial bridges 128 between the handles 16′ as well as theabove-described geometry of the bristle field 26 can be seen again inthe frontal view according to FIG. 37 . The support core 24 is realizedin a trapezoidal manner in cross section. Once again, each product group200′ preferably consists of five brushes.

In the case of the brush shown in FIGS. 38 and 39 , a trough in thehandle 16′ can be provided with a structure such as, for instance, astructure on the edge 162 or on the bottom of the trough. The form ofthe structure can comprise nubs, grooves, lamellae 163 or similar aswell as combinations thereof.

In the case of the brush shown in FIGS. 38-40 , two rows 34 of bristles,which converge in the direction of the end of the bristle stem 18 remotefrom the neck element 32 (said bristle stem tapering in this directionas does the support core) and which, as illustrated in FIG. 41 ,protrude from the top surface of the support core in an outwardlyinclined manner (i.e. not substantially vertically but also notradially), are arranged on the top surface of the support core 24 orbristle stem 18. In addition, once again there are two rows 34 ofbristles which protrude substantially horizontally from the support core14 or from the bristle stem 18.

In this case too, the cap-like extension 30 of the layer/casing 28surrounds the free end of the support core or of the bristle stem 18remote from the neck element 32. In the case of said brush, the secondplastics material component is injected onto the rear end of the handle16′ remote from the neck element 32, the second plastics materialcomponent overlapping a large part of the surface both at the front andat the rear on the handle 16′, whilst it covers a considerable part ofthe surface on the rear side on the neck element 32 (cf. FIG. 29 ) andcompletely covers the surface of the support core 24.

It is, however, also possible for the bottom side of the support corenot to be covered by the second plastics material component analogous toFIG. 29 . On the front and on the rear side in each case, the handle 16′of the brush comprises a trough-shaped indentation 17 for a better hold,as can be seen in FIG. 40 . On the rear side of the handle 16′ (cf. FIG.39 ) the second material component is guided in an elongated indentation19 of the neck element 32. As the injection point 51″ lies at the rearend of the handle 16′, the second plastics material component thus flowsfrom there through the trough-shaped indentation 17 of the handle andthe elongated indentation 19 of the neck element 32 up to the supportcore where it finally (in the corresponding bristle field cavity)realizes the layer or casing 28 with the bristles 20. FIG. 38 shows thesupport points against which the support elements 74 of the bristlefield cavity 50 abut (cf. analogously FIG. 13 ) and prevent the supportcore 24 from being moved in the radial direction and, where applicable,the openings for the individual bristles 20 to be formed from closing. Ahot runner system is provided as a rule for said variant so that thesecond plastics material component does not harden prematurely along itsrelatively long flow path.

A product group 200″ with brushes which are very similar to the brushesshown in FIGS. 38-41 is shown in FIGS. 42-43 . Just the form of thehandles 16′ deviates from the oval handle shape according to FIGS. 38-40.

The present handle shape of the brushes is substantially rectangular andcomprises a side indentation 131 in each case at the sides. This isrelated to the fact that in the present case the individual brushes ofthe product group 200″ are connected by means of two material bridges128, 128′, the material bridges 128 being formed from the first plasticsmaterial component and the material bridges 128′ being formed from thesecond plastics material component.

The material bridges 128 from the first plastics material component arearranged in each case in the rear region of the handle 16′ and thematerial bridges 128′ from the second plastics material component arearranged in each case in the front region of the handle 16′. In the caseof said development, an injection point for the second plastics materialcomponent does not have to be present on each brush.

The handles 16′ (including the neck element and support core) which areinjected initially from the first plastics material component arearranged closely together. In addition, the handles 16′, in the regionof the second material bridge 128′ (to be subsequently injected),comprise transitions 132 on the top or rear surface, by means of whichthe second plastic material component can be distributed. Consequently,an injection point for the second plastics material component does nothave to be provided on each product or each brush. Said product group200″ preferably also consists of five brushes in each case.

Finally, FIGS. 44-46 show a further variant of an interdental brushwhich comprises on the rear end of the handle 16′ a notch 134 forplacing the brush onto a corresponding holder 140 or, for instance, ontoa beaker or a glass. The embodiment which is shown schematically as anexample is an interdental brush with an extrusion-coated wire or supportcore 24 which projects from the neck element 32 and carries a bristlefield 26.

The material of the at least one plastics material component for thehandle 16′ can be chosen such that the two side flanks 136 (or clampingarms) of the handle 16′ surrounding the notch 134 are developed in aresilient manner and thus, where applicable, are able to be mounted ontothe holder 140, the glass or the beaker among other things in a positivelocking and frictional locking manner. The handle 16′ or the handle 16′and the neck element 32 can also be injected from two (or more)different plastics material components. In the preferred embodiment, thenotch 134 is extrusion-coated with a border 135 of a second or furtherplastics material component which regularly provides a soft component.As a result, the hold of the brush on the respective holder 140 can beimproved further. In the present case, the border 135 is realized in anH-shaped manner, which can be advantageous for the handling. The bottomends of the side flanks 136 are preferably completely surrounded by thesoft component. As can be seen in the side view according to FIG. 45 ,the side flanks 136 taper toward their bottom end.

A notch 134 and border 135 of this type can obviously also be providedin an interdental brush with a support core injected from plasticsmaterial, as is illustrated in FIGS. 23-43 (as well as in correspondingproduct groups).

Apart from this, in the case of the embodiments according to FIGS. 23 to46 , the injection point for the first plastics material component 51′lies in a preferred manner in the handle region. Depending on thedevelopment, one or more injection points per product or product groupare conceivable. Preferably one injection point is provided, theplastics material component being distributed in the individual productand by means of the material bridges.

The respective brushes according to FIGS. 23 to 46 can be injected ineach case in the parting plane of a two-part injection mold and can beeasily removed from said mold, which enables particularly cost-effectiveand efficient production. The injection mold for said embodimentregularly does not need any neck mold parts or clamping punches either.

The development variants shown in said document are obviously given byway of example. Within the framework of the present invention, theindividual characteristics and elements of said development variants caneasily be combined with other development variants.

The descriptions given for specific figures can also obviously betransferred to other figures which show identical or similarcharacteristics and in which the characteristics are not described inthe same detail.

Included in a further development:

-   -   1. A method for producing a brush, in particular an interdental        brush (10), using the injection molding method, which brush        comprises a bristle-carrying stem (18), which defines a        longitudinal direction (22) and has an elongated support core        (24), and a bristle field (26) with bristles (20) which protrude        from the bristle-carrying stem (18), said method having the        following steps:        -   closing a bristle field cavity (50) of an injection mold            (42) which comprises a bristle field cavity opening (54) and            serves for producing the bristle-carrying stem (18) and the            bristles (20),        -   inserting the support core (24) in the longitudinal            direction (22) through the bristle field cavity opening (54)            into the closed bristle field cavity (50),        -   fixing the support core (24) inserted into the bristle field            cavity (54) to avoid a movement of the support core (24) in            the longitudinal direction (22) and        -   introducing plastics material into the bristle field cavity            (50) to realize a layer on the support core (24) and the            bristles (20) which protrude from said support core in an            integral manner.    -   2. The method as claimed in development 1, including:        -   preparing an injection mold (42) having a fixing element            (64′) and at least two bristle field mold parts (48)            which—in the closed state—define the closed bristle field            cavity (50), wherein the bristle field cavity (50) comprises            the bristle field cavity opening (54) on an end face (52),        -   moving the bristle field mold parts (48) into the closed            state;        -   then introducing the support core (24) in the longitudinal            direction (22) through the bristle cavity opening (54) into            the closed bristle field cavity (50),        -   fixing the support core (24) by means of the fixing element            (64′) and        -   introducing the plastics material into the bristle field            cavity (50) for realizing the bristles (20) and the layer on            the support core (24).    -   3. The method as claimed in development 1 or 2, wherein the        support core (24) is fixed outside the bristle field (26) to be        formed, preferably outside the bristle field cavity (50) and the        plastics material is introduced through the bristle field cavity        opening (54) into the bristle field cavity (50).    -   4. The method as claimed in one of developments 1 to 3,        characterized in that the injection mold (42) comprises at least        one neck mold part (56) and the support core (24) is fixed in        the region of the neck mold part (56).    -   5. The method as claimed in development 4, characterized in that        the injection mold (42) comprises two neck mold parts (56)        which—in the closed state—define a neck cavity (58) with a neck        cavity opening (60), when the plastics material is injected the        neck cavity opening (60) is arranged at the bristle field cavity        opening (54) and a neck layer, preferably a neck shell (32), is        injected about the support core (24) at the same time as the        layer (28) and the bristles (20) are integrally injected.    -   6. The method as claimed in one of developments 1 to 5, wherein        the support core (24) is clampingly fixed by means of a pair of        clamping punches (64) which can be moved from a rest position        toward one another into a clamping position.    -   7. The method as claimed in development 5, wherein the support        core is clampingly fixed by means of a pair of clamping punches        (64) which can be moved from a rest position toward one another        into a clamping position during the injection molding and the        clamping punches (64) project into the interior of the neck        cavity (58) in the clamping position and are flowed around by        the plastics material during injection molding.    -   8. The method as claimed in development 7, wherein the support        core (24) is completely surrounded in the circumferential        direction by the clamping punches (64) which comprise teeth        (112) which mesh with one another preferably in the clamping        position and are moved into the clamping position such that a        relevant fixing portion (88) of the support core (24) remains        free of plastics material.    -   9. The method as claimed in one of developments 1 to 8, wherein        the support core (24) is centered in the bristle field cavity        (50) by means of the bristle field mold parts (48), preferably        by means of support elements (74) which protrude in the        direction toward the interior of the bristle field cavity (50),        at several support points (38) which are spaced apart from one        another in the longitudinal direction (22).    -   10. The method as claimed in development 9, wherein the support        core (24) is centered by means of the support elements (74)        between bristles (20) which are to be formed and are spaced        apart from one another in the longitudinal direction (22).    -   11. The method as claimed in development 9 or 10, wherein the        support elements (74) protrude by between 0.08 mm and 0.16 mm        and preferably by between 0.1 mm and 0.14 mm.    -   12. The method as claimed in one of developments 9 to 11,        wherein during the injection molding of the plastics material, a        film of plastics material with a thickness of between 0.01 mm        and 0.03 mm and preferably between 0.015 mm and 0.025 mm is        formed between the support element (74) and the support core        (24).    -   13. The method as claimed in one of developments 9 to 12,        wherein the support core (24) is supported by means of the        support elements (74) which follow one after another—in the        longitudinal direction (22)—offset in an angular manner in each        case preferably by at least approximately 90°.    -   14. The method as claimed in one of developments 1 to 13,        wherein the support core (24) is formed by a metal wire, in        particular a spring steel wire.    -   15. The method as claimed in one of developments 1 to 14,        wherein the layer is realized in such a manner that it forms a        casing of the support core (24) in the region of the        bristle-carrying stem (18).    -   16. The method as claimed in development 2 and at all events as        claimed in one of developments 3 to 15, wherein the bristle        field mold parts (48), and where applicable the neck mold parts        (56), which are moved into the closed state, are moved, together        with the support core (24) which is inserted into the bristle        field cavity (50) and fixed, to a handle cavity (68) with handle        mold parts (66) of the injection mold (42) which form a handle        cavity opening (70) such that the bristle field cavity opening        (54) or a further neck cavity opening (62) and the handle cavity        opening (70) lie closely together.    -   17. The method as claimed in development 16, wherein the        plastics material is injected into the handle cavity (68) and        from said cavity is introduced through the handle cavity opening        (70) into the bristle field cavity (50), where applicable into        the neck cavity (58) and through the same into the bristle        cavity (50).    -   18. A brush, in particular an interdental brush produced        according to the method as claimed in one of the developments 1        to 17, which comprises a bristle-carrying stem (18) with an        elongated support core (24) and a bristle field (26) with        bristles (20) which protrude from the bristle-carrying stem        (18), wherein a layer of plastics material is injected onto the        support core (24), preferably to form a casing (28), and the        bristles (20) which protrude from the layer are injected        integrally with the layer.    -   19. The brush as claimed in development 18, wherein a fixing        portion (88) of the support core (24) which lies outside the        bristle field (26) is exposed at least in part, preferably        completely.    -   20. The brush as claimed in development 18 or 19, wherein the        support core (24) is partially exposed at support points (38) in        the region of the bristle field (26) or is only coated by a        plastics material film which, compared to the remaining regions        of the layer or casing (28), is thin.    -   21. The brush as claimed in one of developments 18 to 20,        wherein the bristles (20) protrude at least approximately        radially from the bristle-carrying stem (18), in rows (34) of        bristles which extend in the longitudinal direction (22) and are        distributed in the circumferential direction, preferably in a        uniform manner and are arranged in bristle planes (36) which        extend at right angles to the longitudinal direction (22) and        are preferably spaced apart at a constant spacing.    -   22. A injection mold for producing a brush, in particular an        interdental brush (10), according to the method as claimed in        one of developments 1 to 17, having at least two bristle field        mold parts (48) which—in the closed state—define a bristle field        cavity (50) for producing the bristle-carrying stem (18) and the        bristles (20), wherein on one end face (52), the bristle field        cavity (50) comprises a bristle field cavity opening (54),        through which an elongated support core (24) is insertable in        the longitudinal direction (22) into the bristle field cavity        (50), and having a fixing element (64′) for fixing the support        core inserted into the bristle field cavity (50).    -   23. The injection mold as claimed in development 22, wherein        there are two neck mold parts (56) which define a neck cavity        (58) with a neck cavity opening (60), wherein the fixing element        (64′) is associated with the neck mold parts (56) and—in the        closed state of the injection mold (42)—the neck cavity opening        (60) is arranged at the bristle field cavity opening (54).    -   24. The injection mold as claimed in development 23, wherein in        the closed position there is a handle cavity (68) with handle        mold parts (66) which define a handle cavity opening (70),        wherein the bristle field mold parts (48), which are moved into        the closed state, can be moved together with the support core        inserted into the bristle field cavity (50) and the neck mold        parts (56) to the handle mold parts (66) such that the bristle        field cavity (50), the neck cavity (58) and the handle cavity        (68) together realize an injection cavity (72).

The invention claimed is:
 1. An interdental brush comprising: a handlehaving a flattened shape and comprising at least one trough-shapedindentation on at least one of an upper side and an under side; abristle-carrying stem which defines a longitudinal direction and has anelongated support core; a bristle field comprising bristles whichprotrude from the bristle-carrying stem, the bristles formed from anintegral layer disposed on the support core; and a neck element whichconnects the support core to the handle, wherein the handle, the supportcore and the neck element are integrally molded from a first plasticsmaterial component, the integral layer is formed from a second plasticsmaterial component that at least partially covers the handle and theneck element, and is at least partially disposed in the at least onetrough-shaped indentation of the handle, and the at least onetrough-shaped indentation is partially surrounded by an edge whichmerges into a channel-like indentation of the neck element.
 2. Theinterdental brush as claimed in claim 1, wherein the at least onetrough-shaped indentation is provided with a structure.
 3. Theinterdental brush as claimed in claim 2, wherein the structure isarranged on an edge or on a bottom of the at least one trough-shapedindentation.
 4. The interdental brush as claimed in claim 2, wherein thestructure includes at least one of nubs, grooves, and lamellae.
 5. Theinterdental brush as claimed in claim 1, wherein the at least onetrough-shaped indentation is at least one of closed and open, and if thetrough-shaped indentation is closed, an edge of the trough-shapedindentation is continuous, and, if the trough-shaped indentation isopen, at least at one end of the trough-shaped indentation is open. 6.The interdental brush as claimed in claim 1, wherein the integral layeris disposed on the support core flush with the neck element.
 7. Theinterdental brush as claimed in claim 1, wherein the neck element isfully covered by the second plastics material component.
 8. Theinterdental brush as claimed in claim 1, wherein a length of the brushis in a range of 35 to 70 mm.
 9. The interdental brush as claimed inclaim 1, wherein a height of the brush is in a range of 0.8 to 2.8 mm.10. The interdental brush as claimed in claim 1, wherein the handleincludes at least one through hole.
 11. The interdental brush as claimedin claim 10, wherein the at least one through hole is provided in the atleast one trough-shaped indentation of the handle.
 12. The interdentalbrush as claimed in claim 10, wherein a further plastics materialcomponent is disposed in at least one of the at least one trough-shapedindentation and the at least one through hole.
 13. The interdental brushas claimed in claim 1, wherein the second plastics material component isinjected onto a rear end of the handle, remote from the neck element,and the second plastics material component overlaps a large part of asurface of the handle, while covering a substantial part of a surface ona rear side of the neck element and covering a surface of the supportcore completely or on all sides except a bottom side.
 14. Theinterdental brush as claimed in claim 1, wherein a width of the brush isbetween 3 and 12 mm.
 15. The interdental brush as claimed in claim 1,wherein a width of the brush is between 5 and 8 mm.
 16. An interdentalbrush comprising: a handle; a bristle-carrying stem which defines alongitudinal direction and has an elongated support core; a bristlefield comprising bristles which protrude from the bristle-carrying stem,the bristles formed from an integral layer disposed on the support core;and a neck element comprising a longitudinal, channel-like indention andwhich connects the support core to the handle, wherein the handle, thesupport core and the neck element are integrally molded from a firstplastics material component, the integral layer is formed from a secondplastics material component that at least partially covers the handleand the neck element, and is at least partially disposed in thelongitudinal, channel-like indention of the neck element, and thesupport core is not surrounded or is only surrounded in part by thelayer.
 17. The interdental brush as claimed in claim 16, wherein thesupport core has a diameter that is smaller than a diameter of the neckelement.
 18. The interdental brush as claimed in claim 16, wherein thehandle has a plate-like shape and comprises trough-shaped indentationson at least one of an upper side and an under side.
 19. The interdentalbrush as claimed in claim 18, wherein the second plastics materialcomponent extends from the trough-shaped indentations of the handlethrough the channel-like indention of the neck element up to the supportcore to form the integral layer with the bristles.